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Antarctica is Earth’s southernmost continent, underlying the South Pole. It is situated in the Antarctic region of the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.0 million km2 (5.4 million sq mi), it is the fifth-largest continent in area after Asia, Africa, North America, and South America. About 98% of Antarctica is covered by ice, which averages at least 1.6 kilometres (1.0 mi) in thickness.

Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is considered a desert, with annual precipitation of only 200 mm (8 inches) along the coast and far less inland. There are no permanent human residents but anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Only cold-adapted plants and animals survive there, including penguins, seals, nematodes, Tardigrades, mites, many types of algae and other microorganisms, and tundra vegetation.

Although myths and speculation about a Terra Australis (“Southern Land”) date back to antiquity, the first confirmed sighting of the continent is commonly accepted to have occurred in 1820 by the Russian expedition of Mikhail Lazarev and Fabian Gottlieb von Bellingshausen. The continent, however, remained largely neglected for the rest of the 19th century because of its hostile environment, lack of resources, and isolation. The first formal use of the name “Antarctica” as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. The Antarctic Treaty was signed in 1959 by twelve countries; to date, forty-six countries have signed the treaty. The treaty prohibits military activities and mineral mining, supports scientific research, and protects the continent’s ecozone. Ongoing experiments are conducted by more than 4,000 scientists of many nationalities and with various research interests.


Centered asymmetrically around the South Pole and largely south of the Antarctic Circle, Antarctica is the southernmost continent and is surrounded by the Southern Ocean; alternatively, it may be considered to be surrounded by the southern Pacific, Atlantic, and Indian Oceans, or by the southern waters of the World Ocean. It covers more than 14,000,000 km2 (5,400,000 sq mi), making it the fifth-largest continent, about 1.3 times as large as Europe. The coastline measures 17,968 km (11,165 mi) and is mostly characterized by ice formations, as the following table shows:

Coastal types around Antarctica (Drewry, 1983)
Type Frequency
Ice shelf (floating ice front) 44%
Ice walls (resting on ground) 38%
Ice stream/outlet glacier (ice front or ice wall) 13%
Rock 5%
Total 100%


Antarctica is the coldest place on Earth. The coldest natural temperature ever recorded on Earth was −89.2 °C (−128.6 °F) at the Russian Vostok Station in Antarctica on 21 July 1983. For comparison, this is 11 °C (20 °F) colder than subliming dry ice. Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 cm (4 in) per year, on average. Temperatures reach a minimum of between −80 °C (−112 °F) and −90 °C (−130 °F) in the interior in winter and reach a maximum of between 5 °C (41 °F) and 15 °C (59 °F) near the coast in summer. Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it.

East Antarctica is colder than its western counterpart because of its higher elevation. Weather fronts rarely penetrate far into the continent, leaving the center cold and dry. Despite the lack of precipitation over the central portion of the continent, ice there lasts for extended time periods. Heavy snowfalls are not uncommon on the coastal portion of the continent, where snowfalls of up to 1.22 metres (48 in) in 48 hours have been recorded.

Antarctica is colder than the Arctic for two reasons. First, much of the continent is more than 3 kilometres (2 mi) above sea level, and temperature decreases with elevation. Second, the Arctic Ocean covers the north polar zone: the ocean’s relative warmth is transferred through the icepack and prevents temperatures in the Arctic regions from reaching the extremes typical of the land surface of Antarctica.

 Given the latitude, long periods of constant darkness or constant sunlight create climates unfamiliar to human beings in much of the rest of the world. The aurora australis, commonly known as the southern lights, is a glow observed in the night sky near the South Pole created by the plasma-full solar winds that pass by the Earth. Another unique spectacle is diamond dust, a ground-level cloud composed of tiny ice crystals. It generally forms under otherwise clear or nearly clear skies, so people sometimes also refer to it as clear-sky precipitation. A sun dog, a frequent atmospheric optical phenomenon, is a bright “spot” beside the true sun.

Flora and fauna

The climate of Antarctica does not allow extensive vegetation. A combination of freezing temperatures, poor soil quality, lack of moisture, and lack of sunlight inhibit plant growth. As a result, plant life is limited to mostly mosses and liverworts. The autotrophic community is made up of mostly protists. The flora of the continent largely consists of lichens, bryophytes, algae, and fungi. Growth generally occurs in the summer, and only for a few weeks at most.

 There are more than 200 species of lichens and about 50 species of bryophytes, such as mosses. Seven hundred species of algae exist, most of which are phytoplankton. Multicolored snow algae and diatoms are especially abundant in the coastal regions during the summer. There are two species of flowering plants found in the Antarctic Peninsula: the Antarctic hair grass and the Antarctic pearlwort.
Few terrestrial vertebrates live in Antarctica.  Invertebrate life includes microscopic mites. Recently ancient ecosystems consisting of several types of bacteria have been found living trapped deep beneath glaciers. The flightless midge Belgica antarctica, just 12 millimeters (0.5 in) in size, is the largest purely terrestrial animal in Antarctica. The Snow Petrel is one of only three birds that breed exclusively in Antarctica.

A variety of marine animals exist and rely, directly or indirectly, on the phytoplankton. Antarctic sea life includes penguins, blue whales, orcas, colossal squids and fur seals. The Emperor penguin is the only penguin that breeds during the winter in Antarctica, while the Adélie Penguin breeds farther south than any other penguin. The Rockhopper penguin has distinctive feathers around the eyes, giving the appearance of elaborate eyelashes. King penguins, Chinstrap penguins, and Gentoo Penguins also breed in the Antarctic.

Antarctic territories

Antarctica, Argentina territorial claim.svg Antarctica, Australia territorial claim.svg Antarctica, Chile territorial claim.svg Antarctica, France territorial claim.svg Antarctica, New Zealand territorial claim.svg Antarctica, Norway territorial claim.svg Antarctica, United Kingdom territorial claim.svg
Argentina Australia Chile France New Zealand Norway United Kingdom
Main article: Antarctic territorial claims
Date Country Territory Claim limits
1908  United Kingdom  British Antarctic Territory 20°W to 80°W
1923  New Zealand Ross Dependency 150°W to 160°E
1924  France French Southern and Antarctic Lands Adélie Land 142°2′E to 136°11′E
1929  Norway  Peter I Island 68°50′S 90°35′W / 68.833°S 90.583°W / -68.833; -90.583 (Peter I Island)
1933  Australia Australia Australian Antarctic Territory 160°E to 142°2′E and
136°11′E to 44°38′E
1939  Norway  Queen Maud Land 44°38′E to 20°W
1940  Chile Antártica Chilena Province Antártica 53°W to 90°W
1943  Argentina  Argentine Antarctica 25°W to 74°W
None Unclaimed territory
(Marie Byrd Land)
90°W to 150°W
(except the Peter I Island)

The Argentine, British, and Chilean claims all overlap, and have caused friction. The areas shown as Australia’s and New Zealand’s claims were British territory until they were handed over following the countries’ independence. Australia currently claims the largest area. Australia and New Zealand both recognise the British claim, and vice-versa.

Countries interested in participating in a possible territorial division of Antarctica

This group of countries participating as members of Antarctica Treaty have a territorial interest in the Antarctic continent:

  •  Brazil has a designated ‘zone of interest’ that is not an actual claim.
  •  Peru has formally reserved its right to make a claim.
  •  Russia has reserved its right to claim “territories discovered by Russians”, which potentially may refer to the entire continent.
  •  South Africa has formally reserved its right to make a claim.
  •  Spain has formally reserved its right to make a claim.
  •  United States has formally reserved its right to make a claim.

-Let’s discover more interesting things about Antarctica!


Oceania (sometimes Oceanica) is a geographical, and often geopolitical, region consisting of numerous lands—mostly islands in the Pacific Ocean and vicinity. The term “Oceania” was coined in 1831 by French explorer Dumont d’Urville. The term is also sometimes used to denote a continent comprising Australia and proximate Pacific islands, and is one of eight terrestrial ecozones.

The boundaries of Oceania are defined in a number of ways. Most definitions include Australia, New Zealand, and New Guinea, and all or part of the Malay Archipelago. Ethnologically, the islands that are included in Oceania are divided into the subregions of Melanesia, Micronesia, and Polynesia.


Oceania is traditionally understood as being composed of three regions: Micronesia, Melanesia and Polynesia. As with any region, however, interpretations vary; increasingly, geographers and scientists divide Oceania into Near Oceania and Remote Oceania.

Most of Oceania consists of island nations comprising thousands of coral atolls and volcanic islands, with small human populations. Australia is the only continental country but Indonesia has land borders with Papua New Guinea, East Timor, and Malaysia. If the Australia-New Guinea continent is included then the highest point is Puncak Jaya in Papua at 4,884 m (16,024 ft) and the lowest point is Lake Eyre, Australia at 16 m (52 ft) below sea level.

Territories and regions

Descriptions of the regions and constituents of Oceania vary according to source. The table below shows the subregions and countries of Oceania as broadly categorised according to the scheme for geographic subregions used by the United Nations.  These territories and regions are subject to various additional categorisations, of course, depending on the source and purpose of each description.

Name of region, followed by countries
and their flags
Population Population density
(per km²)
 Australia 7,686,850 22,028,000 2.7 Canberra  
 New Zealand 268,680 4,108,037 14.5 Wellington  
Dependencies/Territories of Australia:
 Christmas Island 135 1,493 3.5 Flying Fish Cove  
 Cocos (Keeling) Islands 14 632 45.1 West Island  
Australia Coral Sea Islands 3        
 Norfolk Island 35 1,866 53.3 Kingston  
 Fiji 18,270 856,346 46.9 Suva  
 Indonesia (Oceanian part only) 499,852 4,211,532 8.4 Jakarta  
 New Caledonia (France) 19,060 240,390 12.6 Nouméa  
 Papua New Guinea 462,840 5,172,033 11.2 Port Moresby  
 Solomon Islands 28,450 494,786 17.4 Honiara  
 Vanuatu 12,200 240,000 19.7 Port Vila  
 Federated States of Micronesia 702 135,869 193.5 Palikir  
 Guam (USA) 549 160,796 292.9 Hagåtña  
 Kiribati 811 96,335 118.8 South Tarawa  
 Marshall Islands 181 73,630 406.8 Majuro  
 Nauru 21 12,329 587.1 Yaren  
 Northern Mariana Islands (USA) 477 77,311 162.1 Saipan  
 Palau 458 19,409 42.4 Melekeok  
United States Wake Island (USA) 2     Wake Island  
 American Samoa (USA) 199 68,688 345.2 Pago Pago, Fagatogo  
 Cook Islands (NZ) 240 20,811 86.7 Avarua  
 Easter Island (Chile) 163.6 3,791 23.1 Hanga Roa  
 French Polynesia (France) 3,961 257,847 61.9 Papeete  
 Hawaii (USA) 28,311 1,283,388 72.8 Honolulu  
 Niue (NZ) 260 2,134 8.2 Alofi  
 Pitcairn Islands (UK) 5 47 10 Adamstown  
 Samoa 2,944 179,000 63.2 Apia  
 Tokelau (NZ) 10 1,431 143.1  
 Tonga 748 106,137 141.9 Nukuʻalofa  
 Tuvalu 26 11,146 428.7 Funafuti  
 Wallis and Futuna (France) 274 15,585 56.9 Mata-Utu  
Total 9,037,695 38,894,851 4.3  
Total minus mainland Australia 1,350,845 17,844,851 13.2

 -Enjoy the following videos about Oceania!


Asia is the world’s largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.6% of the Earth’s total surface area (or 29.9% of its land area) and with approximately 4 billion people, it hosts 60% of the world’s current human population. During the 20th century Asia’s population nearly quadrupled.

Asia is traditionally defined as part of the landmass of Eurasia — with the western portion of the latter occupied by Europe — located to the east of the Suez Canal, east of the Ural Mountains and south of the Caucasus Mountains (or the Kuma-Manych Depression) and the Caspian and Black Seas. It is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean and on the north by the Arctic Ocean. Given its size and diversity, Asia — a toponym dating back to classical antiquity — is more a cultural concept incorporating a number of regions and peoples than a homogeneous physical entity.

The wealth of Asia differs very widely among and within its regions, due to its vast size and huge range of different cultures, environments, historical ties and government systems. In terms of nominal GDP, Japan has the largest economy on the continent and the second largest in the world. In purchasing power parity terms, however, China has the largest economy in Asia and the second largest in the world.

Physical geography

Medieval Europeans considered Asia as a continent a distinct landmass. The European concept of the three continents in the Old World goes back to Classical Antiquity, but during the Middle Ages was notably due to 7th century Spanish scholar Isidore of Sevilla. The demarcation between Asia and Africa (to the southwest) is the Isthmus of Suez and the Red Sea. The boundary between Asia and Europe is conventionally considered to run through the Dardanelles, the Sea of Marmara, the Bosporus, the Black Sea, the Caucasus Mountains, the Caspian Sea, the Ural River to its source and the Ural Mountains to the Kara Sea near Kara, Russia. While this interpretation of tripartite continents (i.e., of Asia, Europe and Africa) remains common in modernity, discovery of the extent of Africa and Asia have made this definition somewhat anachronistic. This is especially true in the case of Asia, which has several regions that would be considered distinct landmasses if these criteria were used (for example, Southern Asia and Eastern Asia).

In the far northeast of Asia, Siberia is separated from North America by the Bering Strait. Asia is bounded on the south by the Indian Ocean (specifically, from west to east, the Gulf of Aden, Arabian Sea and Bay of Bengal), on the east by the waters of the Pacific Ocean (including, counterclockwise, the South China Sea, East China Sea, Yellow Sea, Sea of Japan, Sea of Okhotsk and Bering Sea) and on the north by the Arctic Ocean. Australia (or Oceania) is to the southeast.

Some geographers do not consider Asia and Europe to be separate continents, as there is no logical physical separation between them. For example, Sir Barry Cunliffe, the emeritus professor of European archeology at Oxford, argues that Europe has been geographically and culturally merely “the western excrescence of the continent of Asia.” Geographically, Asia is the major eastern constituent of the continent of Eurasia with Europe being a northwestern peninsula of the landmass – or of Afro-Eurasia: geologically, Asia, Europe and Africa comprise a single continuous landmass (save the Suez Canal) and share a common continental shelf. Almost all of Europe and most of Asia sit atop the Eurasian Plate, adjoined on the south by the Arabian and Indian Plate and with the easternmost part of Siberia (east of the Cherskiy Range) on the North American Plate.

In geography, there are two schools of thought. One school follows historical convention and treats Europe and Asia as different continents, categorizing subregions within them for more detailed analysis. The other school equates the word “continent” with a geographical region when referring to Europe, and use the term “region” to describe Asia in terms of physiography. Since, in linguistic terms, “continent” implies a distinct landmass, it is becoming increasingly common to substitute the term “region” for “continent” to avoid the problem of disambiguation altogether.

Given the scope and diversity of the landmass, it is sometimes not even clear exactly what “Asia” consists of. Some definitions exclude Turkey, the Middle East, Central Asia and Russia while only considering the Far East, Southeast Asia and the Indian subcontinent to compose Asia, especially in the United States after World War II. The term is sometimes used more strictly in reference to the Asia-Pacific region, which does not include the Middle East or Russia, but does include islands in the Pacific Ocean—a number of which may also be considered part of Australasia or Oceania, although Pacific Islanders are not considered Asian.

Political geography

Name of region and
territory, with flag
Population Population density
(per km²)
Central Asia:
 Kazakhstan 2,724,927 15,666,533 5.7 Astana
 Kyrgyzstan 198,500 5,356,869 24.3 Bishkek
 Tajikistan 143,100 7,211,884 47.0 Dushanbe
 Turkmenistan 488,100 5,179,573 9.6 Ashgabat
 Uzbekistan 447,400 28,268,441 57.1 Tashkent
Eastern Asia:
 Hong Kong 1,092 7,008,300 6,417.9
 South Korea 98,480 49,232,844 490.7 Seoul
 Japan 377,835 127,288,628 336.1 Tokyo
 Macau[18] 25 460,823 18,473.3
 Mongolia 1,565,000 2,996,082 1.7 Ulaan Baatar
 North Korea 120,540 23,479,095 184.4 Pyongyang
 People’s Republic of China 9,640,821 1,322,044,605 134.0 Beijing
 Republic of China 35,980 22,920,946 626.7 Taipei
Northern Asia:
 Russia 17,075,400 142,200,000 26.8 Moscow
Southeastern Asia:
 Brunei 5,770 381,371 66.1 Bandar Seri Begawan
 Burma (Myanmar) 676,578 47,758,224 70.3 Naypyidaw
 Cambodia 181,035 13,388,910 74 Phnom Penh
 East Timor (Timor-Leste) 15,007 1,108,777 73.8 Dili
 Indonesia 1,919,440 230,512,000 120.1 Jakarta
 Laos 236,800 6,677,534 28.2 Vientiane
 Malaysia 329,847 27,780,000 84.2 Kuala Lumpur
 Philippines 300,000 92,681,453 308.9 Manila
 Singapore 704 4,608,167 6,545.7 Singapore
 Thailand 514,000 65,493,298 127.4 Bangkok
 Vietnam 331,690 86,116,559 259.6 Hanoi
Southern Asia:
 Afghanistan 647,500 32,738,775 42.9 Kabul
 Bangladesh 147,570 153,546,901 1040.5 Dhaka
 Bhutan 38,394 682,321 17.8 Thimphu
 India 3,287,263 1,147,995,226 349.2 New Delhi
 Maldives 300 379,174 1,263.3 Malé
 Nepal 147,181 29,519,114 200.5 Kathmandu
 Pakistan 803,940 167,762,049 208.7 Islamabad
 Sri Lanka 65,610 21,128,773 322.0 Sri Jayawardenapura-Kotte
Western Asia:
 Armenia       Yerevan
 Azerbaijan 86,660 8,845,127 102.736 Baku
 Bahrain 665 718,306 987.1 Manama
 Cyprus 9,250 792,604 83.9 Nicosia
 Georgia     64.06 Tbilisi
 Iraq 437,072 28,221,181 54.9 Baghdad
 Iran 1,648,195 70,472,846 42.8 Tehran
 Israel 20,770 7,112,359 290.3 Jerusalem
 Jordan 92,300 6,198,677 57.5 Amman
 Kuwait 17,820 2,596,561 118.5 Kuwait City
 Lebanon 10,452 3,971,941 353.6 Beirut
 Oman 212,460 3,311,640 12.8 Muscat
 Palestine 6,257 4,277,000 683.5 Ramallah
 Qatar 11,437 928,635 69.4 Doha
 Saudi Arabia 1,960,582 23,513,330 12.0 Riyadh
 Syria 185,180 19,747,586 92.6 Damascus
 Turkey       Ankara
 United Arab Emirates 82,880 4,621,399 29.5 Abu Dhabi
 Yemen 527,970 23,013,376 35.4 Sanaá
Total 43,810,582 4,162,966,086 89.07
Note: Part of Egypt (Sinai Peninsula) is geographically in Western Asia

-Finally, enjoy these activities and videos about Asia! (Geography: Asia [Part 1 of 2]) (Geography: Asia [Part 2 of 2])



Africa is the world’s second-largest and second most-populous continent, after Asia. At about 30.2 million km² (11.7 million sq mi) including adjacent islands, it covers 6% of the Earth’s total surface area and 20.4% of the total land area. With a billion people (as of 2009, see table) in 61 territories, it accounts for about 14.72% of the World’s human population. The continent is surrounded by the Mediterranean Sea to the north, both the Suez Canal and the Red Sea along the Sinai Peninsula to the northeast, the Indian Ocean to the southeast, and the Atlantic Ocean to the west. The continent has 54 states, including Madagascar, various island groups, and the Sahrawi Arab Democratic Republic, a member state of the African Union whose statehood is disputed by Morocco.

Africa, particularly central eastern Africa, is widely regarded within the scientific community to be the origin of humans and the Hominidae clade (great apes), as evidenced by the discovery of the earliest hominids and their ancestors, as well as later ones that have been dated to around seven million years ago – including Sahelanthropus tchadensis, Australopithecus africanus, A. afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens (modern human) found in Ethiopia being dated to ca. 200,000 years ago.

Africa straddles the equator and encompasses numerous climate areas; it is the only continent to stretch from the northern temperate to southern temperate zones.


Africa is the largest of the three great southward projections from the largest landmass of the Earth. Separated from Europe by the Mediterranean Sea, it is joined to Asia at its northeast extremity by the Isthmus of Suez (transected by the Suez Canal), 163 km (101 miles) wide. (Geopolitically, Egypt’s Sinai Peninsula east of the Suez Canal is often considered part of Africa, as well.) From the most northerly point, Ras ben Sakka in Tunisia, to the most southerly point, Cape Agulhas in South Africa, is a distance of approximately 8,000 km (5,000 miles); from Cape Verde, the westernmost point, to Ras Hafun in Somalia, the most easterly projection, is a distance of approximately 7,400 km (4,600 miles). The coastline is 26,000 km (16,100 miles) long, and the absence of deep indentations of the shore is illustrated by the fact that Europe, which covers only 10,400,000 km² (4,010,000 square miles) – about a third of the surface of Africa – has a coastline of 32,000 km (19,800 miles).

Africa’s largest country is Sudan, and its smallest country is the Seychelles, an archipelago off the east coast. The smallest nation on the continental mainland is The Gambia.

 According to the ancient Romans, Africa lay to the west of Egypt, while “Asia” was used to refer to Anatolia and lands to the east. A definite line was drawn between the two continents by the geographer Ptolemy (85–165 AD), indicating Alexandria along the Prime Meridian and making the isthmus of Suez and the Red Sea the boundary between Asia and Africa. As Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge.

Geologically, Africa includes the Arabian Peninsula; the Zagros Mountains of Iran and the Anatolian Plateau of Turkey mark where the African Plate collided with Eurasia. The Afrotropic ecozone and the Saharo-Arabian desert to its north unite the region biogeographically, and the Afro-Asiatic language family unites the north linguistically.


The climate of Africa ranges from tropical to subarctic on its highest peaks. Its northern half is primarily desert or arid, while its central and southern areas contain both savanna plains and very dense jungle (rainforest) regions. In between, there is a convergence where vegetation patterns such as sahel, and steppe dominate.


The African Union (AU) is a 53 member federation consisting of all of Africa’s states except Morocco. The union was formed, with Addis Ababa as its headquarters, on 26 June 2001. In July 2004, the African Union’s Pan-African Parliament (PAP) was relocated to Midrand, in South Africa, but the African Commission on Human and Peoples’ Rights remained in Addis Ababa. There is a policy in effect to decentralise the African Federation’s institutions so that they are shared by all the states.

The African Union, not to be confused with the AU Commission, is formed by an Act of Union, which aims to transform the African Economic Community, a federated commonwealth, into a state under established international conventions. The African Union has a parliamentary government, known as the African Union Government, consisting of legislative, judicial and executive organs. It is led by the African Union President and Head of State, who is also the President of the Pan African Parliament. A person becomes AU President by being elected to the PAP, and subsequently gaining majority support in the PAP.

The powers and authority of the President of the African Parliament derive from the Union Act, and the Protocol of the Pan African Parliament, as well as the inheritance of presidential authority stipulated by African treaties and by international treaties, including those subordinating the Secretary General of the OAU Secretariat (AU Commission) to the PAP. The government of the AU consists of all-union (federal), regional, state, and municipal authorities, as well as hundreds of institutions, that together manage the day-to-day affairs of the institution.

There are clear signs of increased networking among African organisations and states. In the civil war in the Democratic Republic of the Congo (former Zaire), rather than rich, non-African countries intervening, neighbouring African countries became involved (see also Second Congo War). Since the conflict began in 1998, the estimated death toll has reached 5 million.

Political associations such as the African Union offer hope for greater co-operation and peace between the continent’s many countries. Extensive human rights abuses still occur in several parts of Africa, often under the oversight of the state. Most of such violations occur for political reasons, often as a side effect of civil war. Countries where major human rights violations have been reported in recent times include the Democratic Republic of the Congo, Sierra Leone, Liberia, Sudan, Zimbabwe, and Côte d’Ivoire.

Territories and regions

The countries in this table are categorised according to the scheme for geographic subregions used by the United Nations.

Name of region and
territory, with flag
Population Density
(per km²)
Eastern Africa: 6,384,904 316,053,651 49.5
Burundi Burundi 27,830 8,988,091 322.9 Bujumbura
Comoros Comoros 2,170 752,438 346.7 Moroni
Djibouti Djibouti 23,000 516,055 22.4 Djibouti
Eritrea Eritrea 121,320 5,647,168 46.5 Asmara
Ethiopia Ethiopia 1,127,127 85,237,338 75.6 Addis Ababa
Kenya Kenya 582,650 39,002,772 66.0 Nairobi
Madagascar Madagascar 587,040 20,653,556 35.1 Antananarivo
Malawi Malawi 118,480 14,268,711 120.4 Lilongwe
Mauritius Mauritius 2,040 1,284,264 629.5 Port Louis
Mayotte Mayotte (France) 374 223,765 489.7 Mamoudzou
Mozambique Mozambique 801,590 21,669,278 27.0 Maputo
Réunion Réunion (France) 2,512 743,981 296.2 Saint-Denis
Rwanda Rwanda 26,338 10,473,282 397.6 Kigali
Seychelles Seychelles 455 87,476 192.2 Victoria
Somalia Somalia 637,657 9,832,017 15.4 Mogadishu
Tanzania Tanzania 945,087 41,048,532 43.3 Dodoma
Uganda Uganda 236,040 32,369,558 137.1 Kampala
Zambia Zambia 752,614 11,862,740 15.7 Lusaka
Middle Africa: 6,613,253 121,585,754 18.4
Angola Angola 1,246,700 12,799,293 10.3 Luanda
Cameroon Cameroon 475,440 18,879,301 39.7 Yaoundé
Central African Republic Central African Republic 622,984 4,511,488 7.2 Bangui
Chad Chad 1,284,000 10,329,208 8.0 N’Djamena
Republic of the Congo Congo 342,000 4,012,809 11.7 Brazzaville
Democratic Republic of the Congo Democratic Republic of the Congo 2,345,410 68,692,542 29.2 Kinshasa
Equatorial Guinea Equatorial Guinea 28,051 633,441 22.6 Malabo
Gabon Gabon 267,667 1,514,993 5.6 Libreville
São Tomé and Príncipe São Tomé and Príncipe 1,001 212,679 212.4 São Tomé
Northern Africa: 8,533,021 211,087,622 24.7
Algeria Algeria 2,381,740 34,178,188 14.3 Algiers
Egypt Egypt 1,001,450 83,082,869 82.9 Cairo
Libya Libya 1,759,540 6,310,434 3.6 Tripoli
Morocco Morocco 446,550 34,859,364 78.0 Rabat
Sudan Sudan 2,505,810 41,087,825 16.4 Khartoum
Tunisia Tunisia 163,610 10,486,339 64.1 Tunis
Western Sahara Sahrawi Arab Democratic Republic 266,000 405,210 1.5 El Aaiún
Spanish and Portuguese territories in Northern Africa:
Canary Islands Canary Islands (Spain) 7,492 1,694,477 226.2 Las Palmas de Gran Canaria,
Santa Cruz de Tenerife
Ceuta Ceuta (Spain) 20 71,505 3,575.2
Madeira Madeira Islands (Portugal) 797 245,000 307.4 Funchal
Melilla Melilla (Spain) 12 66,411 5,534.2
Southern Africa: 2,693,418 56,406,762 20.9
Botswana Botswana 600,370 1,990,876 3.3 Gaborone
Lesotho Lesotho 30,355 2,130,819 70.2 Maseru
Zimbabwe Zimbabwe 390,580 11,392,629 29.1 Harare
Namibia Namibia 825,418 2,108,665 2.6 Windhoek
South Africa South Africa 1,219,912 49,052,489 40.2 Bloemfontein, Cape Town, Pretoria
Swaziland Swaziland 17,363 1,123,913 64.7 Mbabane
Western Africa: 6,144,013 296,186,492 48.2
Benin Benin 112,620 8,791,832 78.0 Porto-Novo
Burkina Faso Burkina Faso 274,200 15,746,232 57.4 Ouagadougou
Cape Verde Cape Verde 4,033 429,474 107.3 Praia
Côte d'Ivoire Côte d’Ivoire 322,460 20,617,068 63.9 Abidjan,Yamoussoukro
The Gambia Gambia 11,300 1,782,893 157.7 Banjul
Ghana Ghana 239,460 23,832,495 99.5 Accra
Guinea Guinea 245,857 10,057,975 40.9 Conakry
Guinea-Bissau Guinea-Bissau 36,120 1,533,964 42.5 Bissau
Liberia Liberia 111,370 3,441,790 30.9 Monrovia
Mali Mali 1,240,000 12,666,987 10.2 Bamako
Mauritania Mauritania 1,030,700 3,129,486 3.0 Nouakchott
Niger Niger 1,267,000 15,306,252 12.1 Niamey
Nigeria Nigeria 923,768 149,229,090 161.5 Abuja
Saint Helena, Ascension and Tristan da Cunha Saint Helena, Ascension and Tristan da Cunha (UK) 410 7,637 14.4 Jamestown
Senegal Senegal 196,190 13,711,597 69.9 Dakar
Sierra Leone Sierra Leone 71,740 6,440,053 89.9 Freetown
Togo Togo 56,785 6,019,877 106.0 Lomé
Africa Total 30,368,609 1,001,320,281 33.0

 -Do you like to know more about Africa? Enjoy these activities!


Central America  is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. Most of Central America is considered to be part of the Mesoamerican biodiversity hotspot.


Central America has an area of 524,000 square kilometers (202,000 sq mi), or almost 0.1% of the Earth’s surface. As of 2009, its population was estimated at 41,739,000. It has a density of 79 people per square kilometer or 206 people per square mile.

Physiographically, Central America is the tapering isthmus of southern North America, extending from the Isthmus of Tehuantepec in southern Mexico southeastward to the Isthmus of Panama where it connects to the Colombian Pacific Lowlands in northwestern South America. Alternatively, the Trans-Mexican Volcanic Belt delimits the region on the north. Central America has an area of some 592,000 square kilometres. The Pacific Ocean lies to the southwest, the Caribbean Sea lies to the northeast, and the Gulf of Mexico lies to the north. Most of Central America rests atop the Caribbean Plate.

The region is geologically active, with volcanic eruptions and earthquakes occurring from time to time. In 1976 Guatemala was hit by a major earthquake, killing 23,000 people; Managua, the capital of Nicaragua, was devastated by earthquakes in 1931 and 1972, the last one killed about 5,000 people; three earthquakes devastated El Salvador, one in 1986 and two in 2001; one earthquake devastated northern and central Costa Rica in 2009 killing at least 34 people; in Honduras a powerful earthquake killed 7 people in 2009.

Volcanic eruptions are common in the region. In 1968 the Arenal Volcano, in Costa Rica, erupted and killed 87 people. Fertile soils from weathered volcanic lavas have made it possible to sustain dense populations in the agriculturally productive highland areas.

Central America has many mountain ranges; the longest are the Sierra Madre de Chiapas, the Cordillera Isabelia and the Cordillera de Talamanca. Between the mountain ranges lie fertile valleys that are suitable for the people; in fact most of the population of Honduras, Costa Rica and Guatemala live in valleys. Valleys are also suitable for the production of coffee, beans and other crops.

Human geography

Geopolitically, Central America has traditionally consisted of the following countries:

Name of territory, with flag

Area (km²) Population (July 2009 est.) Population density (per km²) Capital

Official language

 Belize 22,966 307,000 13 Belmopan English
 Costa Rica 51,100 4,579,000 90 San José Spanish
 El Salvador 21,040 6,163,000 292 San Salvador Spanish
 Guatemala 108,890 14,027,000 129 Guatemala City Spanish
 Honduras 112,090 7,466,000 67 Tegucigalpa Spanish
 Nicaragua 130,373 5,743,000 44 Managua Spanish
 Panama 78,200 3,454,000 44 Panama City Spanish
Total 523,780 41,739,000 80  

Many modern definitions of Central America include Belize, and Panama, which did not exist upon the formation of the Federal Republic of Central America, a short-lived union created after most of the region gained independence from Spain in 1821. The territory now occupied by Belize was originally contested by the United Kingdom and the Spanish Empire and, later, Guatemala (which has considered it, wholly or partially, an eastern department); it became a British colony (British Honduras) in 1871 and gained independence in 1981.

Panama, situated on the Isthmus of Panama, is sometimes regarded as a transcontinental territory. Because of the Panama Canal, it is considered part of both North America and South America. For much of its post-Columbian history, Panama was culturally linked to South America. Panama was a possession of the Viceroyalty of New Granada, and then, following independence, became a part of la Gran Colombia (Greater Colombia). Only after independence from Colombia in 1903 did some begin to regard Panama as a North or Central American entity.

-Enjoy these funny exercises about Central America!


North America  is the northern continent of the Americas,  situated in the Earth’s northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific Ocean. To the southeast lies South America.

North America covers an area of about 24,709,000 square kilometers (9,540,000 square miles), about 4.8 percent of the planet’s surface or about 16.5 percent of its land area. As of July 2008, its population was estimated at nearly 529 million people. It is the third-largest continent in area, after Asia and Africa, and the fourth-largest in population, after Asia, Africa, and Europe.

Geography and extent

North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, the Americas, or simply America (which is sometimes considered a single continent and North America a subcontinent). North America’s only land connection to South America is at the Isthmus of Panama. The continent is generally delimited on the southeast by the Darién watershed along the Colombia-Panama border, or at the Panama Canal; according to other sources, its southern limit is the Isthmus of Tehuantepec, Mexico, with Central America tapering and extending southeastward to South America. Before the Central American isthmus was raised, the region had been underwater. The islands of the West Indies delineate a submerged former land bridge, which had connected North America and South America via what are now Florida and Venezuela. Much of North America is on the North American Plate.

The continental coastline is long and irregular. The Gulf of Mexico is the largest body of water indenting the continent, followed by Hudson Bay. Others include the Gulf of Saint Lawrence and the Gulf of California.

There are numerous islands off the continent’s coasts: principally, the Arctic Archipelago, the Bahamas, Turks & Caicos, the Greater and Lesser Antilles, the Aleutian Islands (some of which are in the eastern hemisphere proper), the Alexander Archipelago, the many thousand islands of the British Columbia Coast, Newfoundland and Greenland, a self-governing Danish island, and the world’s largest, is on the same tectonic plate (the North American Plate) and is part of North America geographically. Bermuda is not part of the Americas, but is an oceanic island which was formed on the fissure of the Mid-Atlantic Ridge over 100 million years ago. The nearest landmass to it is Cape Hatteras, North Carolina, and it is often thought of as part of North America, especially given its historical, political and cultural ties to Virginia and other parts of the continent.

Human geography

The prevalent languages in North America are English, Spanish, and French. The term Anglo-America is used to refer to the anglophone countries of the Americas: namely Canada (where English and French are co-official) and the United States, but also sometimes Belize and parts of the Caribbean. Latin America refers to the other areas of the Americas (generally south of the United States) where the Romance languages, derived from Latin, of Spanish and Portuguese (but French speaking countries are not usually included) predominate: the other republics of Central America (but not always Belize), part of the Caribbean (not the Dutch, English or French speaking areas), Mexico, and most of South America (except Guyana, Suriname, French Guiana (FR), and The Falkland Islands (UK).

The French language has historically played a significant role in North America and retains a distinctive presence in some regions. Canada is officially bilingual. French is the official language of the province of Quebec and is co-official with English in the province of New Brunswick. Other French-speaking locales include the province of Ontario (the official language is English, but there is an estimated 500,000 Franco-Ontarians), the French West Indies and Saint-Pierre and Miquelon, as well as the U.S. state of Louisiana, where French is also an official language. Haiti is included with this group based on historical association but Haitians speak Creole and French. Similarly there remains small segments in Saint Lucia and the Commonwealth of Dominica that speak unique French and creole languages alongside their English speaking majorities.

Socially and culturally, North America presents a well-defined entity. Canada and the United States have a similar culture and similar traditions as a result of both countries being former British colonies. A common cultural and economic market has developed between the two nations because of the strong economic and historical ties. Spanish-speaking North America shares a common past as former Spanish colonies. In Mexico and the Central American countries where civilizations like the Maya developed, indigenous people preserve traditions across modern boundaries. Central American and Spanish-speaking Caribbean nations have historically had more in common due to geographical proximity and the fact that, after winning independence from Spain. Northern Mexico, particularly cities such as Monterrey, Tijuana, Ciudad Juárez, and Mexicali are strongly influenced by the culture and way of life of the U.S. Immigration to the United States and Canada remains a significant attribute of many nations close to the southern border of the U.S. As the British Empire and its influences declined, the Anglophone Caribbean states have witnessed the economic influence of northern North America increase on the region. In the Anglophone Caribbean this influence is in part due to the fact that the majority of English-speaking Caribbean countries have populations of less than 200,000 people and many of these countries now have expatriate diasporas living abroad that are larger than those remaining at home.

Economically, Canada and the United States are the wealthiest and most developed nations in the continent, followed by Mexico, a newly industrialized country; the countries of Central America and the Caribbean are at various levels of development. The most important trade blocs are the Caribbean Community and Common Market (CARICOM), the North American Free Trade Agreement (NAFTA), and the recently signed Central American Free Trade Agreement (CAFTA)—the last of these being an example of the economic integration sought by the nations of this sub-region as a way to improve their financial status.

Demographically, North America is a racially and ethnically diverse continent. Its three main racial groups are Whites, Mestizos and Blacks (chiefly African-Americans and Afro-Caribbeans).  There is a significant minority of Native Americans and Asians among other less numerous groups.

Countries and territories

North America is often divided into subregions but no universally accepted divisions exist. Central America comprises the southern region of the continent, but its northern terminus varies between sources. Geophysically, the region starts at the Isthmus of Tehuantepec in Mexico (namely the Mexican states of Campeche, Chiapas, Tabasco, Quintana Roo, and Yucatán). The United Nations geoscheme includes Mexico in Central America; conversely, the European Union excludes both Mexico and Belize from the area. Geopolitically, Mexico is frequently not considered a part of Central America.

Northern America is used to refer to the northern countries and territories of North America: Canada, the United States, Greenland, Bermuda, and St. Pierre and Miquelon. They are often considered distinct from the southern portion of the Americas, which largely comprise Latin America. The term Middle America is sometimes used to collectively refer to Mexico, the nations of Central America, and the Caribbean.

Country or
(July 2008 est.)
Population density
(per km²)
Anguilla Anguilla (UK) 102 14,108 138.3 The Valley
Antigua and Barbuda Antigua and Barbuda 443 84,522 190.8 St. John’s
Aruba Aruba (Netherlands) 193 101,541 526.1 Oranjestad
The Bahamas Bahamas 10,070 307,451 30.5 Nassau
Barbados Barbados 431 281,968 654.2 Bridgetown
Belize Belize 22,966 301,270 13.1 Belmopan
Bermuda Bermuda (UK) 53 66,536 1255.4 Hamilton
British Virgin Islands British Virgin Islands (UK) 153 24,041 157.1 Road Town
Canada Canada 9,984,670 33,212,696 3.7 Ottawa
Cayman Islands Cayman Islands (UK) 262 47,862 182.7 George Town
France Clipperton Island (France) 6 0 0.0
Costa Rica Costa Rica 51,100 4,195,914 82.1 San José
Cuba Cuba 110,860 11,423,952 103.0 Havana
Dominica Dominica 754 72,514 96.2 Roseau
Dominican Republic Dominican Republic 48,730 9,507,133 195.1 Santo Domingo
El Salvador El Salvador 21,040 7,066,403 335.9 San Salvador
Greenland Greenland (Denmark) 2,166,086 57,564 0.027 Nuuk
Grenada Grenada 344 90,343 262.6 St. George’s
Guadeloupe Guadeloupe (France) 1,780 452,776 254.4 Basse-Terre
Guatemala Guatemala 108,890 13,002,206 119.4 Guatemala City
Haiti Haiti 27,750 8,924,553 321.6 Port-au-Prince
Honduras Honduras 112,090 7,639,327 68.2 Tegucigalpa
Jamaica Jamaica 10,991 2,804,332 255.1 Kingston
Martinique Martinique (France) 1,100 436,131 396.5 Fort-de-France
Mexico Mexico 1,923,040 109,955,400 57.2 Mexico City
Montserrat Montserrat (UK) 102 5,079 49.8 Plymouth; Brades
United States Navassa Island (USA) 5 0 0.0
Netherlands Antilles Netherlands Antilles (Netherlands) 960 225,369 234.8 Willemstad
Nicaragua Nicaragua 120,254 5,785,846 48.1 Managua
Panama Panama 78,200 3,309,679 42.3 Panama City
Puerto Rico Puerto Rico (USA) 8,870 3,958,128 446.2 San Juan
Saint Barthélemy Saint Barthélemy (France) 21 7,492 356.8 Gustavia
Saint Kitts and Nevis Saint Kitts and Nevis 261 39,817 152.6 Basseterre
Saint Lucia Saint Lucia 616 159,585 259.1 Castries
Collectivity of Saint Martin Saint Martin (France) 54 29,376 544.0 Marigot
Saint Pierre and Miquelon Saint Pierre and Miquelon (France) 242 7,044 29.1 Saint-Pierre
Saint Vincent and the Grenadines Saint Vincent and the Grenadines 389 118,432 304.5 Kingstown
Trinidad and Tobago Trinidad and Tobago 5,128 1,047,366 204.2 Port of Spain
Turks and Caicos Islands Turks and Caicos Islands (UK) 430 22,352 52.0 Cockburn Town
United States United States 9,826,630 303,824,640 33.2 Washington, D.C.
United States Virgin Islands U.S. Virgin Islands (USA) 346 109,840 317.5 Charlotte Amalie
Total 24,646,412 528,720,588 22.9

-Finally, here you will find suitable activities about America!


Cycling Water

Water water everywhere and always moving around. Even the smallest water molecule at the bottom of the ocean is moving. It just moves really slowly. We’re going to talk about the hydrologic cycle. This is the path water takes when it moves through the oceans, through the sky and through life on land. It’s a never ending cycle that keeps life on Earth alive.

Just Flowing Through

Water cycles and flows through ecosystems. Water is recycled on a global scale. It’s actually a cycle through the biosphere, not just through local ecosystems. It may flow from one ecosystem to another on its way from the air to the land and back to the oceans. Also, a great amount of fresh water below the surface of the Earth that is cycled over long periods of time.

The Overview

Even though there is no real starting place, we’ll start the cycle in the atmosphere. Water in the atmosphere is found in clouds and water vapor. Slowly the entire atmosphere circulates around the planet. When weather is created one of the most common results is precipitation. Precipitation is the process of water condensing in the atmosphere. It could be rain, snow, drizzle, fog, dew, or hail. Whatever path, the water comes out of the atmosphere and makes it to the surface. Scientists also use the term hydrological cycle to when discussing water’s movement through the biosphere.

Once on the surface, water is still moving around. Snow can melt and become rivers that flow into the oceans. Water can collect underground (groundwater). Water can collect in the oceans. Over 60% of the surface of the planet is covered by water. Beyond collecting, water can return to the atmosphere. Water moves from the ground or oceans into the atmosphere through a process called evaporation. It’s a process that happens on a molecular level when the molecules of water are really energized and rise into the air.

Now you’ve got water in the air and water on land. Organisms all over the Earth need water to survive. Although it’s a small amount when compared to oceans, every living creature is filled with water. Our cells are mainly composed of water. The human body is 80% water. Eventually, when an organism dies, the water is returned to the system, but you should know that living things borrow water on a regular basis.

Life Of A Water Molecule

So you’re a water molecule. Chances are you’ll stay a water molecule and won’t ever be broken down. The world likes to keep its water around. You’re moving through the hydrologic cycle. You evaporate, fall in rain, and drain in a river. Not a lot of excitement. But how much time does it take? Scientists think that if you are lucky enough to be evaporated into a cloud that you spend about ten days floating around the atmosphere. If you’re unlucky enough to be at the bottom of the ocean, or stuck in a glacier, you might spend tens of thousands of years without moving. 

-Finally, enjoy these activities and videos about the water cycle! (The water cycle song) (The Earth’s Water Cycle) (Water cycle lesson)


The geography of South America contains many diverse regions and climates. Geographically, South America is generally considered a continent forming the southern portion of the American landmass, south and east of the Panama-Colombia border by most authorities, or south and east of the Panama Canal by some. South and North America are sometimes considered a single continent or supercontinent, while constituent regions are infrequently considered subcontinents. Geopolitically and geographically, all of Panama – including the segment east of the Panama Canal in the isthmus – is generally considered a part of North America alone and among the countries of Central America.

South America became attached to North America only recently (geologically speaking) with the formation of the Isthmus of Panama some 3 million years ago, which resulted in the Great American Interchange. The Andes, likewise a comparatively young and seismically restless mountain range, run down the western edge of the continent; the land to the east of the Andes is largely tropical rain forest, the vast Amazon River basin. The continent also contains drier regions such as eastern Patagonia and the extremely arid Atacama desert.

The South American continent also includes various islands, most of which belong to countries on the continent. The Caribbean territories are grouped with North America. The South American nations that border the Caribbean Sea — including Colombia, Venezuela, Guyana, Suriname, and French Guiana — are also known as Caribbean South America.

Topography and geology

The geographical structure of South America is deceptively simple for a continent-sized landmass. The continent’s topography is often likened to a huge bowl owing to its flat interior almost ringed by high mountains. With the exception of narrow coastal plains on the Pacific and Atlantic Oceans, there are three main topographic features: the Andes, a central lowland, and the extensive Brazilian and Guiana Highlands in the east.

The Andes are a Cenozoic mountain range formed (and still forming) by the continuing collision of the American and Pacific tectonic plates. In their northern and central reaches the Andes are quite wide and contain extensive plateaux such as the Altiplano and a number of major valleys such as the Rio Magdalena. These contain three of the world’s highest capitals: Bogotá, Quito and highest of all, La Paz, Bolivia. The southern Andes have been eroded by the Patagonian Ice Sheet and are much lower and narrower. There are a number of large glaciers in the northern part, but from latitude 19°S to 28°S the climate is so arid that no permanent ice can form even on the highest peaks. Permafrost, however, is widespread in this section of the Altiplano and continuous above 5,600 metres (18,373 ft).

The climate of the coastal belt west of the Andes shows violent contrasts, including two of the world’s wettest regions in the Colombian Chocó and southern Chile and the world’s driest desert, the Atacama. This dry area is cooled by the Humboldt Current and upwelling, giving rise to the largest fisheries in the world. There are two small transition zones between the perhumid and perarid regions: around Guayaquil with summer rain, and the Mediterranean climate region of central Chile. Both these regions have highly erratic rainfall strongly influenced by El Niño events, which bring major floods. In contrast, the high plateaux of the Andes are drier than normal during El Niño episodes.

The very fertile soils from the erosion of the Andes formed the basis for the continent’s only pre-Columbian state civilizations: those of the Inca Empire and its predecessors (Chavín, Nazca, Mochica, etc.). The area is still a major agricultural region. The Altiplano contains many rare minerals such as copper, tin, mercury ore. The Atacama is mined for its nitrates. East of the Andes in Peru is regarded as the most important biodiversity hotspot in the world with its unique forests that form the western edge of the world’s largest rainforest, the Amazon Rainforest.

East of the Andes is a large lowland drained by a small number of rivers, including the two largest in the world by drainage area – the Amazon River and the more southerly Paraná River. The other major river of this central lowland is the Orinoco River, which has a natural channel linking it with the Amazon. Most of this central lowland is sparsely populated because the soils are heavily leached, but in the south is the very fertile pampas of Argentina – one of the world’s major food-producing regions where wheat and beef cattle are pre-eminent. The natural vegetation of the northern lowlands are either savanna in the northern llanos and southern campos, or tropical rainforest throughout most of the Amazon basin. Efforts to develop agriculture, outside of fertile floodplains of rivers descending from the Andes, have been largely failures because of the soils. Cattle have long been raised in the llanos of northern Colombia and Venezuela, but petroleum is now the dominant industry in the northern lowlands, making Venezuela the richest country in the continent.

The eastern highlands are much older than the Andes, being pre-Cambrian in origin, but are still rugged in places, especially in the wet tepuis of Venezuela, Guyana and Roraima. The Amazon River has cut a large valley through a former highland, and to the east is a relatively low plateau comprising the Nordeste and Southeast regions of Brazil. In the north of this region is the arid sertão, a poor region consistently affected by extremely erratic rainfall, and the humid zona da mata, once home of the unique Atlantic Rainforest with many species not found in the Amazon, and now a centre for sugarcane. Further south, the main land use is coffee, while São Paulo is the economic heart of the continent with its industry.

South of about Santa Catarina, the highlands fade out to low plains in Uruguay.

East of the Andes in Argentina, there are a number of rugged, generally dry lslands, the highest of which is the Sierra de Cordoba near the city of that name. Argentine Patagonia is a Paleozoic plateau now heavily dissected by rivers flowing from the Andes.


The largest country in South America by far, in both area and population, is Brazil, followed by Argentina. Regions in South America include the Andean States, the Guianas, the Southern Cone, and Eastern South America.

Name of territory,
with flag
(July 2009 est.)
Population density
(per km²)
Argentina Argentina 2,766,890 40,913,584 14.8 Buenos Aires
Bolivia Bolivia 1,098,580 9,775,246 8.9 La Paz, Sucre
Brazil Brazil 8,511,965 198,739,269 23.3 Brasília
Chile Chile 756,950 16,601,707 21.9 Santiago
Colombia Colombia 1,138,910 45,644,023 40.1 Bogotá
Ecuador Ecuador 283,560 14,573,101 51.4 Quito
Falkland Islands Falkland Islands (UK) 12,173 3,140 0.26 Stanley
French Guiana French Guiana (France) 83,534 221,500 2.7 Cayenne
Guyana Guyana 214,970 772,298 3.6 Georgetown
Paraguay Paraguay 406,750 6,995,655 17.2 Asunción
Peru Peru 1,285,220 29,546,963 23.0 Lima
South Georgia and the South Sandwich Islands South Georgia and
South Sandwich Islands (UK)
3,903 0 0 Grytviken
Suriname Suriname 163,270 481,267 2.9 Paramaribo
Uruguay Uruguay 176,220 3,494,382 19.8 Montevideo
Venezuela Venezuela 912,050 26,814,843 29.4 Caracas

Finally, do these activities and watch these videos to know more about South America! (Visiting South America) (The Mighty Amazon)


Circle of 12 gold stars on a blue background.The European Union (EU) is an economic and political union between 27 member countries, located primarily in Europe. Committed to regional integration, the EU was established by the Treaty of Maastricht on 1 November 1993 upon the foundations of the European Communities. With over 500 million citizens, the EU combined generates an estimated 28% share (US$ 16.45 trillion in 2009) of the nominal gross world product and about 21.3% (US$14.8 trillion in 2009) of the PPP gross world product.

The EU has developed a single market through a standardised system of laws which apply in all member states, ensuring the free movement of people, goods, services, and capital. It maintains common policies on trade, agriculture, fisheries  and regional development. Sixteen member states have adopted a common currency, the euro, constituting the Eurozone. The EU has developed a limited role in foreign policy, having representation at the World Trade Organization, G8, G-20 major economies and at the United Nations. It enacts legislation in justice and home affairs, including the abolition of passport controls by the Schengen Agreement between 22 EU and 3 non-EU states.

As an international organisation, the EU operates through a hybrid system of supranationalism and intergovernmentalism. In certain areas, decisions are made through negotiation between member states, while in others, independent supranational institutions are responsible without a requirement for unanimity between member states. Important institutions of the EU include the European Commission, the Council of the European Union, the European Council, the Court of Justice of the European Union, and the European Central Bank. The European Parliament is elected every five years by member states’ citizens, to whom the citizenship of the European Union is guaranteed.

The EU traces its origins from the European Coal and Steel Community formed among six countries in 1951 and the Treaty of Rome formed in 1957 by the same states. Since then, the EU has grown in size through enlargement, and in power through the addition of policy areas to its remit.


After World War II, moves towards European integration were seen by many as an escape from the extreme forms of nationalism which had devastated the continent. One such attempt to unite Europeans was the European Coal and Steel Community which, while having the modest aim of centralised control of the previously national coal and steel industries of its member states, was declared to be “a first step in the federation of Europe”.  The originators and supporters of the Community include Jean Monnet, Robert Schuman, Paul Henri Spaak, and Alcide de Gasperi. The founding members of the Community were Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany.

In 1957, these six countries signed the Treaties of Rome which extended the earlier cooperation within the European Coal and Steel Community and created the European Economic Community, (EEC) establishing a customs union and the European Atomic Energy Community (Euratom) for cooperation in developing nuclear energy. In 1967 the Merger Treaty created a single set of institutions for the three communities, which were collectively referred to as the European Communities (EC), although commonly just as the European Community.

In 1973, the Communities enlarged to include Denmark, Ireland, and the United Kingdom. Norway had negotiated to join at the same time but Norwegian voters rejected membership in a referendum and so Norway remained outside. In 1979, the first direct, democratic elections to the European Parliament were held.

Greece joined in 1981, and Spain and Portugal in 1986. In 1985, the Schengen Agreement led the way toward the creation of open borders without passport controls between most member states and some non-member states. In 1986, the European flag began to be used by the Community and the Single European Act was signed.

In 1990, after the fall of the Iron Curtain, the former East Germany became part of the Community as part of a newly united Germany. With enlargement towards Eastern and Central Europe on the agenda, the Copenhagen criteria for candidate members to join the European Union were agreed.

The European Union was formally established when the Maastricht Treaty came into force on 1 November 1993, and in 1995 Austria, Sweden, and Finland joined the newly established EU. In 2002, euro notes and coins replaced national currencies in 12 of the member states. Since then, the eurozone has increased to encompass sixteen countries. In 2004, the EU saw its biggest enlargement to date when Malta, Cyprus, Slovenia, Estonia, Latvia, Lithuania, Poland, the Czech Republic, Slovak Republic, and Hungary joined the Union.

On 1 January 2007, Romania and Bulgaria became the EU’s newest members. In the same year Slovenia adopted the euro,  followed in 2008 by Cyprus and Malta, and by Slovakia in 2009. In June 2009, the 2009 Parliament elections were held leading to a renewal of Barroso’s Commission Presidency, and in July 2009 Iceland formally applied for EU membership. On 1 December 2009, the Lisbon Treaty came into force after a protracted and controversial birth. This reformed many aspects of the EU but in particular created a permanent President of the European Council, the first of which is Herman van Rompuy, and a strengthened High Representative, Catherine Ashton.

Member states

The European Union is composed of 27 sovereign Member States: Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland, Portugal, Romania, Slovak Republic, Slovenia, Spain, Sweden, and the United Kingdom.

The Union’s membership has grown from the original six founding states–Belgium, France, (then-West) Germany, Italy, Luxembourg and the Netherlands–to the present day 27 by successive enlargements as countries acceded to the treaties and by doing so, pooled their sovereignty in exchange for representation in the institutions.

To join the EU a country must meet the Copenhagen criteria, defined at the 1993 Copenhagen European Council. These require a stable democracy that respects human rights and the rule of law; a functioning market economy capable of competition within the EU; and the acceptance of the obligations of membership, including EU law. Evaluation of a country’s fulfilment of the criteria is the responsibility of the European Council.

No member state has ever left the Union, although Greenland (an autonomous province of Denmark) withdrew in 1985. The Lisbon Treaty now provides a clause dealing with how a member leaves the EU.

There are three official candidate countries, Croatia, Macedonia and Turkey. Albania, Bosnia and Herzegovina, Montenegro, Serbia and Iceland are officially recognised as potential candidates.  Kosovo is also listed as a potential candidate but the European Commission does not list it as an independent country because not all member states recognise it as an independent country separate from Serbia.

Four Western European countries that have chosen not to join the EU have partly committed to the EU’s economy and regulations: Iceland, which has now applied for membership, Liechtenstein and Norway, which are a part of the single market through the European Economic Area, and Switzerland, which has similar ties through bilateral treaties. The relationships of the European microstates, Andorra, Monaco, San Marino and the Vatican include the use of the euro and other areas of co-operation.


The territory of the EU consists of the combined territories of its 27 member states with some exceptions, outlined below. The territory of the EU is not the same as that of Europe, as parts of the continent are outside the EU, such as Switzerland, Norway, European Russia, and Iceland. Some parts of member states are not part of the EU, despite forming part of the European continent (for example the Isle of Man and Channel Islands (two Crown Dependencies), and the Faroe Islands (a territory of Denmark)). The island country of Cyprus, a member of the EU, is closer to Turkey than to continental Europe and is often considered part of Asia.

Several territories associated with member states that are outside geographic Europe are also not part of the EU (such as Greenland, Aruba, the Netherlands Antilles, and all the non-European British overseas territories). Some overseas territories are part of the EU even though geographically not part of Europe, such as the Azores, the Canary Islands, Madeira, Lampedusa, French Guiana, Guadeloupe, Saint Barthélemy, Martinique, Réunion, Ceuta and Melilla. As well, although being technically part of the EU, EU law is suspended in Northern Cyprus as it is under the de facto control of the Turkish Republic of North Cyprus, a self-proclaimed state that is recognised only by Turkey.

The EU’s member states cover an area of 4,422,773 square kilometres (1,707,642 sq mi). The EU is larger in area than all but six countries, and its highest peak is Mont Blanc in the Graian Alps, 4,807 metres (15,771 ft) above sea level. The landscape, climate, and economy of the EU are influenced by its coastline, which is 65,993 kilometres (41,006 mi) long. The EU has the world’s second-longest coastline, after Canada. The combined member states share land borders with 19 non-member states for a total of 12,441 kilometres (7,730 mi), the fifth-longest border in the world.

Including the overseas territories of member states, the EU experiences most types of climate from Arctic to tropical, rendering meteorological averages for the EU as a whole meaningless. The majority of the population lives in areas with a Mediterranean climate (Southern Europe), a temperate maritime climate (Western Europe), or a warm summer continental or hemiboreal climate (Eastern Europe).

The EU’s population is also highly urbanized, with some 75% of people (and growing, projected to be 90% in 7 states by 2020) living in urban areas. Cities are largely spread out across the EU, although with a large grouping in and around the Benelux and a large amount of urbanization in Spain since it joined the EU. An increasing percentage of this is due to low density urban sprawl which is extending into natural areas. In some cases this urban growth has been due to the influx of EU funds into a region.


The institutions of the EU operate solely within those competencies conferred on it upon the treaties and according to the principle of subsidiarity (which dictates that action by the EU should only be taken where an objective cannot be sufficiently achieved by the member states alone). Law made by the EU institutions is passed in a variety of forms, primarily that which comes into direct force and that which must be passed in a refined form by national parliaments.

Legislative competencies are divided equally, with some exceptions, between the European Parliament and the Council of the European Union while executive tasks are carried out by the European Commission and in a limited capacity by the European Council (not to be confused with the aforementioned Council of the European Union). The interpretation and the application of EU law and the treaties are ensured by the Court of Justice of the European Union. There are also a number of ancillary bodies which advise the EU or operate in a specific area.

European Council

The EU receives its political leadership from the European Council, which usually meets four times a year. It comprises one representative per member state—either its head of state or head of government—plus its President as well as the President of the Commission. The member states’ representatives are assisted by their Foreign Ministers. The European Council uses its leadership role to sort out disputes between member states and the institutions, and to resolve political crises and disagreements over controversial issues and policies. The European Council should not be mistaken for the Council of Europe, an international organisation independent from the EU.

On 19 November 2009, Herman Van Rompuy was chosen as the first President of the European Council and Catherine Ashton was chosen as the High Representative of the Union for Foreign Affairs and Security Policy. They both assumed office on 1 December 2009.


The Council (also called “Council of the European Union” and sometimes referred to as the “Council of Ministers”) forms one half of the EU’s legislature. It consists of a government minister from each member state and meets in different compositions depending on the policy area being addressed. Notwithstanding its different compositions, it is considered to be one single body. In addition to its legislative functions, the Council also exercises executive functions in relations to the Common Foreign and Security Policy.


The European Commission acts as the EU’s executive arm and is responsible for initiating legislation and the day-to-day running of the EU. It is intended to act solely in the interest of the EU as a whole, as opposed to the Council which consists of leaders of member states who reflect national interests. The commission is also seen as the motor of European integration. It is currently composed of 27 commissioners for different areas of policy, one from each member state. The President of the Commission and all the other commissioners are nominated by the Council. Appointment of the Commission President, and also the Commission in its entirety, have to be confirmed by Parliament.


The European Parliament forms the other half of the EU’s legislature. The 736 (soon to be 750) Members of the European Parliament (MEPs) are directly elected by EU citizens every five years. Although MEPs are elected on a national basis, they sit according to political groups rather than their nationality. Each country has a set number of seats and in some cases is divided into sub-national constituencies. The Parliament and the Council of Ministers pass legislation jointly in nearly all areas under the ordinary legislative procedure. This also applies to the EU budget. Finally, the Commission is accountable to Parliament, requiring its approval to take office, having to report back to it and subject to motions of censure from it. The President of the European Parliament carries out the role of speaker in parliament and represents it externally. The president and vice presidents are elected by MEPs every two and a half years.

Fundamental rights

As a product of efforts to establish a written fundamental rights code, the EU drew up the Charter of Fundamental Rights in 2000. The Charter is legally binding since the Lisbon Treaty has come into force.  Also, the Court of Justice gives judgements on fundamental rights derived from the “constitutional traditions common to the member states,” and may even invalidate EU legislation based on its failure to adhere to these fundamental rights.

Although signing the European Convention on Human Rights (ECHR) is a condition for EU membership, the EU itself is not covered by the convention as it is neither a state  nor, prior to the entry into force of the Lisbon treaty, had the competence to accede.  Lisbon Treaty and Protocol 14 to the ECHR have changed this: the first binding the EU to accede to the Convention and the second formally allowing this. Nonetheless the Court of Justice and European Court of Human Rights co-operate to ensure their case-law does not conflict. The EU opposes the death penalty and promotes its world wide abolition. Abolition of the death penalty is a condition for EU membership.

Foreign relations

Foreign policy cooperation between member states dates from the establishment of the Community in 1957, when member states negotiated as a bloc in international trade negotiations under the Common Commercial Policy. Steps for a more wide ranging coordination in foreign relations began in 1970 with the establishment of European Political Cooperation which created an informal consultation process between member states with the aim of forming common foreign policies. It was not, however, until 1987 when European Political Cooperation was introduced on a formal basis by the Single European Act. EPC was renamed as the Common Foreign and Security Policy (CFSP) by the Maastricht Treaty.

The Maastricht Treaty gives the CFSP the aims of promoting both the EU’s own interests and those of the international community as a whole. This includes promoting international co-operation, respect for human rights, democracy, and the rule of law.

The Amsterdam Treaty created the office of the High Representative for the Common Foreign and Security Policy (currently held by Catherine Ashton) to co-ordinate the EU’s foreign policy. The High Representative, in conjunction with the current Presidency, speaks on behalf of the EU in foreign policy matters and can have the task of articulating ambiguous policy positions created by disagreements among member states. The Common Foreign and Security Policy requires unanimity among the now 27 member states on the appropriate policy to follow on any particular issue. The unanimity and difficult issues treated under the CFSP makes disagreements, such as those which occurred over the war in Iraq, not uncommon.

Besides the emerging international policy of the European Union, the international influence of the EU is also felt through enlargement. The perceived benefits of becoming a member of the EU act as an incentive for both political and economic reform in states wishing to fulfil the EU’s accession criteria, and are considered an important factor contributing to the reform of former Communist countries in Central and Eastern Europe. This influence on the internal affairs of other countries is generally referred to as “soft power”, as opposed to military “hard power”.

In the UN, as an observer and working together, the EU has gained influence in areas such as aid due to its large contributions in that field. In the G8, the EU has rights of membership besides chairing/hosting summit meetings and is represented at meetings by the presidents of the Commission and the Council. In the World Trade Organisation (WTO), where all 27 member states are represented, the EU as a body is represented by Trade Commissioner Karel De Gucht.

Single market

Two of the original core objectives of the European Economic Community were the development of a common market, subsequently renamed the single market, and a customs union between its member states. The single market involves the free circulation of goods, capital, people and services within the EU, and the customs union involves the application of a common external tariff on all goods entering the market. Once goods have been admitted into the market they cannot be subjected to customs duties, discriminatory taxes or import quotas, as they travel internally. The non-EU member states of Iceland, Norway, Liechtenstein and Switzerland participate in the single market but not in the customs union. Half the trade in the EU is covered by legislation harmonised by the EU.

Free movement of capital is intended to permit movement of investments such as property purchases and buying of shares between countries. Until the drive towards Economic and Monetary Union the development of the capital provisions had been slow. Post-Maastricht there has been a rapidly developing corpus of ECJ judgements regarding this initially neglected freedom. The free movement of capital is unique insofar as that it is granted equally to non-member states.

The free movement of persons means citizens can move freely between member states to live, work, study or retire in another country. This required the lowering of administrative formalities and recognition of professional qualifications of other states.

The free movement of services and of establishment allows self-employed persons to move between member states in order to provide services on a temporary or permanent basis. While services account for between sixty and seventy percent of GDP, legislation in the area is not as developed as in other areas. This lacuna has been addressed by the recently passed Directive on services in the internal market which aims to liberalise the cross border provision of services. According to the Treaty the provision of services is a residual freedom that only applies if no other freedom is being exercised.

Monetary union

The creation of a European single currency became an official objective of the EU in 1969. However, it was only with the advent of the Maastricht Treaty in 1993 that member states were legally bound to start the monetary union no later than 1 January 1999. On this date the euro was duly launched by eleven of the then fifteen member states of the EU. It remained an accounting currency until 1 January 2002, when euro notes and coins were issued and national currencies began to phase out in the eurozone, which by then consisted of twelve member states. The eurozone has since grown to sixteen countries, the most recent being Slovakia which joined on 1 January 2009.

All other EU member states, except Denmark and the United Kingdom, are legally bound to join the euro when the convergence criteria are met, however only a few countries have set target dates for accession. Sweden has circumvented the requirement to join the euro by not meeting the membership criteria.

The euro is designed to help build a single market by, for example: easing travel of citizens and goods, eliminating exchange rate problems, providing price transparency, creating a single financial market, price stability and low interest rates, and providing a currency used internationally and protected against shocks by the large amount of internal trade within the eurozone. It is also intended as a political symbol of integration and stimulus for more. Since its launch the euro has become the second reserve currency in the world with a quarter of foreign exchanges reserves being in euro.

The euro, and the monetary policies of those who have adopted it in agreement with the EU, are under the control of the European Central Bank (ECB). There are eleven other currencies used in the EU with all but two legally obliged to be switched to the euro. A number of other countries outside the EU, such as Montenegro, use the euro without formal agreement with the ECB.


The Common Agricultural Policy (CAP) is one of the oldest policies of the European Community, and was one of its core aims. The policy has the objectives of increasing agricultural production, providing certainty in food supplies, ensuring a high quality of life for farmers, stabilising markets, and ensuring reasonable prices for consumers. It was, until recently, operated by a system of subsidies and market intervention. Until the 1990s, the policy accounted for over 60% of the then European Community’s annual budget, and still accounts for around 35%.

The policy’s price controls and market interventions led to considerable overproduction, resulting in so-called butter mountains and wine lakes. These were intervention stores of produce bought up by the Community to maintain minimum price levels. In order to dispose of surplus stores, they were often sold on the world market at prices considerably below Community guaranteed prices, or farmers were offered subsidies (amounting to the difference between the Community and world prices) to export their produce outside the Community. This system has been criticised for under-cutting farmers in the developing world.

The overproduction has also been criticised for encouraging environmentally unfriendly intensive farming methods. Supporters of CAP say that the economic support which it gives to farmers provides them with a reasonable standard of living, in what would otherwise be an economically unviable way of life. However, the EU’s small farmers receive only 8% of CAP’s available subsidies.

Since the beginning of the 1990s, the CAP has been subject to a series of reforms. Initially these reforms included the introduction of set-aside in 1988, where a proportion of farm land was deliberately withdrawn from production, milk quotas (by the McSharry reforms in 1992) and, more recently, the ‘de-coupling’ (or disassociation) of the money farmers receive from the EU and the amount they produce (by the Fischler reforms in 2004). Agriculture expenditure will move away from subsidy payments linked to specific produce, toward direct payments based on farm size. This is intended to allow the market to dictate production levels, while maintaining agricultural income levels. One of these reforms entailed the abolition of the EU’s sugar regime, which previously divided the sugar market between member states and certain African-Caribbean nations with a privileged relationship with the EU.


In 2006, the 27 member states of the EU had a gross inland energy consumption of 1,825 million tonnes of oil equivalent (toe). Around 46% of the energy consumed was produced within the member states while 54% was imported. In these statistics, nuclear energy is treated as primary energy produced in the EU, regardless of the source of the uranium, of which less than 3% is produced in the EU.

The EU has had legislative power in the area of energy policy for most of its existence; this has its roots in the original European Coal and Steel Community. The introduction of a mandatory and comprehensive European energy policy was approved at the meeting of the European Council in October 2005, and the first draft policy was published in January 2007.

The Commission has five key points in its energy policy: increase competition in the internal market, encourage investment and boost interconnections between electricity grids; diversify energy resources with better systems to respond to a crisis; establish a new treaty framework for energy co-operation with Russia while improving relations with energy-rich states in Central Asia and North Africa; use existing energy supplies more efficiently while increasing use of renewable energy; and finally increase funding for new energy technologies.

The EU currently imports 82% of its oil, 57% of its gas and 97.48% of its uranium demands. There are concerns that Europe’s dependence on Russian energy is endangering the Union and its member countries. The EU is attempting to diversify its energy supply.


The EU is working to improve cross-border infrastructure within the EU, for example through the Trans-European Networks (TEN). Projects under TEN include the Channel Tunnel, LGV Est, the Fréjus Rail Tunnel, the Öresund Bridge and the Brenner Base Tunnel. In 2001 it was estimated that by 2010 the network would cover: 75,200 kilometres (46,700 mi) of roads; 78,000 kilometres (48,000 mi) of railways; 330 airports; 270 maritime harbours; and 210 internal harbours.

The developing European transport policies will increase the pressure on the environment in many regions by the increased transport network. In the pre-2004 EU members, the major problem in transport deals with congestion and pollution. After the recent enlargement, the new states that joined since 2004 added the problem of solving accessibility to the transport agenda. The Polish road network in particular was in poor condition: at Poland’s accession to the EU, 4,600 roads needed to be upgraded to EU standards, demanding approximately €17 billion.

Another infrastructure project is the Galileo positioning system. Galileo is a proposed Global Navigation Satellite System, to be built by the EU and launched by the European Space Agency (ESA), and is to be operational by 2010. The Galileo project was launched partly to reduce the EU’s dependency on the US-operated Global Positioning System, but also to give more complete global coverage and allow for far greater accuracy, given the aged nature of the GPS system. It has been criticised by some due to costs, delays, and their perception of redundancy given the existence of the GPS system.


The first environmental policy of the European Community was launched in 1972. Since then it has addressed issues such as acid rain, the thinning of the ozone layer, air quality, noise pollution, waste and water pollution. The Water Framework Directive is an example of a water policy, aiming for rivers, lakes, ground and coastal waters to be of “good quality” by 2015. Wildlife is protected through the Natura 2000 programme and covers 30,000 sites throughout Europe. In 2007, the Polish government sought to build a motorway through the Rospuda valley, but the Commission has been blocking construction as the valley is a wildlife area covered by the programme.

In 2007, member states agreed that the EU is to use 20% renewable energy in the future and that is has to reduce carbon dioxide emissions in 2020 by at least 20% compared to 1990 levels. This includes measures that in 2020, one-tenth of all cars and trucks in EU 27 should be running on biofuels. This is considered to be one of the most ambitious moves of an important industrialised region to fight global warming.

At the 2007 United Nations Climate Change Conference, dealing with the successor to the Kyoto Protocol, the EU has proposed at 50% cut in greenhouse gases by 2050. The EU’s attempts to cut its carbon footprint appear to have also been aided by an expansion of Europe’s forests which, between 1990 and 2005, grew 10% in western Europe and 15% in Eastern Europe. During this period they soaked up 126 million metric tons of carbon dioxide, equivalent to 11% of EU emissions from human activities.


Education and science are areas where the EU’s role is limited to supporting national governments. In education, the policy was mainly developed in the 1980s in programmes supporting exchanges and mobility. The most visible of these has been the ERASMUS programme, a university exchange programme which began in 1987. In its first 20 years it has supported international exchange opportunities for well over 1.5 million university and college students and has become a symbol of European student life.

There are now similar programmes for school pupils and teachers, for trainees in vocational education and training, and for adult learners in the Lifelong Learning Programme 2007–2013. These programmes are designed to encourage a wider knowledge of other countries and to spread good practices in the education and training fields across the EU. Through its support of the Bologna process the EU is supporting comparable standards and compatible degrees across Europe.

Culture and sport

Policies affecting cultural matters are mainly set by individual member states. Cultural co-operation between member states has been a concern of the EU since its inclusion as a community competency in the Maastricht Treaty. Actions taken in the cultural area by the EU include the Culture 2000 7-year programme, the European Cultural Month event, the Media Plus programme, orchestras such as the European Union Youth Orchestra and the European Capital of Culture programme – where one or more cities in the EU are selected for one year to assist the cultural development of that city.

In addition, the EU gives grants to cultural projects (totalling 233 in 2004) and has launched a Web portal dedicated to Europe and culture, responding to the European Council’s expressed desire to see the Commission and the member states “promote the networking of cultural information to enable all citizens to access European cultural content by the most advanced technological means”.

Sport is mainly the responsibility of individual member states or other international organisations rather than that of the EU. However, some EU policies have had an impact on sport, such as the free movement of workers which was at the core of the Bosman ruling, which prohibited national football leagues from imposing quotas on foreign players with European citizenship. Under the Treaty of Lisbon sports were given a special status which exempted this sector from many of the EU’s economic rules. This followed lobbying by governing organisations such as the International Olympic Committee and FIFA, due to objections over the applications of free market principles to sport which led to an increasing gap between rich and poor clubs.

-After reading, enjoy the following activities and videos about the European Union! (Timeline of European Union) (What can The European Union do for you?) (50 years of The European Union) (Europe wants well-informed consumers) (Travelling in Europe: The Euro)


This is a list of countries in Europe with their English and domestic language long and short names and associated capital cities.

The divisions between Asia and Europe occur at the Ural Mountains, Ural River and Caspian Sea in the east, the Caucasus Mountains and the Black Sea with its outlets, Bosporus and Dardanelles in the south. Azerbaijan, Georgia, Kazakhstan, Russia and Turkey are considered part of both Europe and Asia. Armenia and Cyprus, which are entirely in Western Asia, are sociopolitically European countries.

Sovereign states

Flag Map English Short Name English Long Name Capital     
Flag of Albania.svg
Europe map albania.png Albania Republic of Albania  Tirana  
Flag of Andorra.svg
Europe map andorra.png Andorra Principality of Andorra  Andorra la Vella
Flag of Armenia.svg
Europe map armenia.png Armenia Republic of Armenia Yerevan
Flag of Austria.svg
Europe map austria.png Austria Republic of Austria Vienna
Flag of Azerbaijan.svg
Europe map azerbaijan.png Azerbaijan Republic of Azerbaijan Baku
Flag of Belarus.svg
Europe map belarus.png Belarus Republic of Belarus Minsk
Flag of Belgium.svg
Europe map belgium.png Belgium Kingdom of Belgium Brussels
Flag of Bosnia and Herzegovina.svg
Europe map bosnia.png Bosnia and Herzegovina Republic of Bosnia and Herzegovina  Sarajevo
Flag of Bulgaria.svg
Europe map bulgaria.png Bulgaria Republic of Bulgaria  Sofia
Flag of Croatia.svg
Europe map croatia.png Croatia Republic of Croatia Zagreb
Flag of Cyprus.svg
Europe map cyprus.png Cyprus Republic of Cyprus Nicosia  
Flag of the Czech Republic.svg
Europe map czechia.png Czechia Czech Republic Prague
Flag of Denmark.svg
Europe map denmark.png Denmark Kingdom of Denmark Copenhagen
Flag of Estonia.svg
Europe map estonia.png Estonia Republic of Estonia Tallinn
Flag of Finland.svg
Europe map finland.png Finland Republic of Finland Helsinki
Flag of France.svg
Europe map france.png France French Republic Paris
Flag of Georgia.svg
Europe map georgia.png Georgia Republic of Georgia  Tbilisi
Flag of Germany.svg
Europe map germany.png Germany Federal Republic of Germany Berlin
Flag of Greece.svg
Europe map greece.png Greece Hellenic Republic Athens
Flag of Hungary.svg
Europe map hungary.png Hungary Republic of Hungary Budapest
Flag of Iceland.svg
Europe map iceland.png Iceland Republic of Iceland Reykjavík
Flag of Ireland.svg
Europe map ireland.png Ireland Republic of Ireland Dublin  
Flag of Italy.svg
Europe map italy.png Italy Italian Republic Rome
Flag of Kazakhstan.svg
Europe map kazakhstan.png Kazakhstan Republic of Kazakhstan Astana
Flag of Latvia.svg
Europe map latvia.png Latvia Republic of Latvia Riga
Flag of Liechtenstein.svg
Europe map liechtenstein.png Liechtenstein Principality of Liechtenstein Vaduz
Flag of Lithuania.svg
Europe map lithuania.png Lithuania Republic of Lithuania Vilnius
Flag of Luxembourg.svg
Europe map luxembourg.png Luxembourg Grand Duchy of Luxembourg Luxembourg City
Flag of Macedonia.svg
Europe map macedonia.png Macedonia Republic of Macedonia Skopje
Flag of Malta.svg
Europe map malta.png Malta Republic of Malta Valletta
Flag of Moldova.svg
Europe map moldova.png Moldova Republic of Moldova Chisinau
Flag of Monaco.svg
Europe map monaco.png Monaco Principality of Monaco Monaco
Flag of Montenegro.svg
Europe map montenegro.png Montenegro Republic of Montenegro  Podgorica  
Flag of the Netherlands.svg
Europe map netherlands.png Netherlands Kingdom of the Netherlands Amsterdam (capital)
The Hague (seat of government)
Flag of Norway.svg
Europe map norway.png Norway Kingdom of Norway Oslo
Flag of Poland.svg
Europe map poland.png Poland Republic of Poland Warsaw
Flag of Portugal.svg
Europe map portugal.png Portugal Portuguese Republic Lisbon
Flag of Romania.svg
Europe map romania.png Romania    Bucharest
Flag of Russia.svg
Europe map russia.png Russia Russian Federation Moscow
Flag of San Marino.svg
Europe map sanmarino.png San Marino Most Serene Republic of San Marino City of San Marino
Flag of Serbia.svg
Europe map serbia.png Serbia Republic of Serbia Belgrade
Flag of Slovakia.svg
Europe map slovakia.png Slovakia Slovak Republic Bratislava
Flag of Slovenia.svg
Europe map slovenia.png Slovenia Republic of Slovenia Ljubljana
Flag of Spain.svg
Europe map spain.png Spain Kingdom of Spain Madrid
Flag of Sweden.svg
Europe map sweden.png Sweden Kingdom of Sweden Stockholm
Flag of Switzerland.svg
Europe map switzerland.png Switzerland Swiss Confederation Bern
Flag of Turkey.svg
Europe map turkey.png Turkey Republic of Turkey Ankara
Flag of Ukraine.svg
Europe map ukraine.png Ukraine    Kiev
Flag of the United Kingdom.svg
Europe map uk.png United Kingdom United Kingdom of Great Britain and Northern Ireland  London  
Flag of the Vatican City.svg
Europe map vatican.png Vatican City
Holy See
State of the Vatican City Vatican City  


Partially recognised states

The following geo-political entities in Europe have partial diplomatic recognition by one or more sovereign states.

Flag Map English Short Name English Long Name Capital
Flag of Abkhazia.svg
Location of Abkhazia in Europe2.png Abkhazia   Sukhumi  
Flag of Kosovo.svg
Kosovo in Balkans.png Kosovo Republic of Kosovo  Pristina
Flag of Nagorno-Karabakh.svg
Location Nagorno-Karabakh en.png Nagorno-Karabakh Nagorno-Karabakh Republic Stepanakert
Flag of the Turkish Republic of Northern Cyprus.svg
TRNC location.svg Northern Cyprus Turkish Republic of Northern Cyprus Lefkoşa
Flag of South Ossetia.svg
Location of South Ossetia in Europe2.png South Ossetia   Tskhinvali  
Flag of Transnistria.svg
Transnistria-map.png Transnistria Pridnestrovian Moldavian Republic Tiraspol  


-Finally enjoy these activities about European countries!


Europe  is, by convention, one of the world’s seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains (or the Kuma-Manych Depression), and the Black Sea to the southeast. Europe is bordered by the Arctic Ocean and other bodies of water to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and the Black Sea and connected waterways to the southeast. Yet the borders for Europe—a concept dating back to classical antiquity—are somewhat arbitrary, as the term continent can refer to a cultural and political distinction or a physiographic one.

Europe is the world’s second-smallest continent by surface area, covering about 10,180,000 square kilometres (3,930,000 sq mi) or 2% of the Earth’s surface and about 6.8% of its land area. Of Europe’s approximately 50 states, Russia is the largest by both area and population, while Vatican City is the smallest. Europe is the third-most populous continent after Asia and Africa, with a population of 731 million or about 11% of the world’s population. However, according to the United Nations (medium estimate), Europe’s share may fall to about 7% by 2050. In 1900, Europe’s share of the world’s population was 25%.


The coast of Europe is heavily indented with bays and gulfs.

The idea of a European “continent” is not universally held. Some geographical texts refer to a Eurasian Continent, or to a European subcontinent, given that Europe is not surrounded by sea and is, in any case, much more a cultural than a geographically definable area.

In terms of shape, Europe is a collection of connected peninsulas. The two largest of these are “mainland” Europe and Scandinavia to the north, divided from each other by the Baltic Sea. Three smaller peninsulas—Iberia, Italy and the Balkans—emerge from the southern margin of the mainland into the Mediterranean Sea, which separates Europe from Africa. Eastward, mainland Europe widens much like the mouth of a funnel, until the boundary with Asia is reached at the Ural Mountains.

Land relief in Europe shows great variation within relatively small areas. The southern regions are mountainous, while moving north the terrain descends from the high Alps, Pyrenees and Carpathians, through hilly uplands, into broad, low northern plains, which are vast in the east. An arc of uplands also exists along the northwestern seaboard, beginning in the western British Isles and continuing along the mountainous, fjord-cut spine of Norway.

This description is simplified. Sub-regions such as Iberia and Italy contain their own complex features, as does mainland Europe itself, where the relief contains many plateaus, river valleys and basins that complicate the general trend. Iceland and the British Isles are special cases. The former is a land unto itself in the northern ocean which is counted as part of Europe, while the latter are upland areas that were once joined to the mainland until rising sea levels cut them off.

The few generalizations that can be made about the relief of Europe make it less than surprising that the continent’s many separate regions provided homes for many separate nations throughout history.

Mountain ranges

Some of Europe’s major mountain ranges are:

  • Ural Mountains, used to separate Europe and Asia
  • Caucasus Mountains, which also separate Europe and Asia, and is the namesake of the Caucasian race, not to be confused with Caucasian peoples
  • Carpathian Mountains, a major mountain range in Central and Southern Europe
  • Alps, the famous mountains known for their spectacular slopes
  • Apennines, which run through Italy
  • Pyrenees, the natural border between France and Spain
  • Cantabrian Mountains, which run across northern Spain
  • Scandinavian Mountains, a mountain range which runs through the Scandinavian Peninsula, includes the Kjølen mountains
  • Dinaric Alps, a mountain range in the Balkans
  • Balkan mountains, a mountain range in central Balkans
  • Scottish highlands ( cairngorms, a ‘low level’ mountain range, in northern and central Scotland.
  • Pennines, very low level mountain range, subject to extreme glacial sculpting, in earlier ice ages, found in northern England.


The following are the longest rivers in Europe alongside their approximate lengths:

  1. Volga –   3,690 km (2,293 mi)
  2. Danube – 2,860 km (1,777 mi)
  3. Ural   –    2,428 km (1,509 mi)
  4. Dnieper – 2,290 km (1,423 mi)
  5. Don   –     1,950 km (1,212 mi)
  6. Pechora – 1,809 km (1,124 mi)
  7. Kama –  1,805 km (1,122 mi)
  8. Oka   –   1,500 km (932 mi)
  9. Belaya – 1,430 km (889 mi)
10. Tisza   –   1,358 km (844 mi)
11. Dniester – 1,352 km (840 mi)
12. Rhine   –   1,236 km (768 mi)
13. Elbe   –   1,091 km (678 mi)
14. Vistula – 1,047 km (651 mi)
15. Tagus   – 1,038 km (645 mi)
16. Daugava – 1,020 km (634 mi)
17. Loire – 1,012 km (629 mi)
18. Ebro – 960 km (597 mi)
19. Nemunas – 937 km (582 mi)
20. Sava – 933 km (580 mi)
21. Oder – 854 km (531 mi)
22. Rhône – 815 km (506 mi)
23. Seine  - 776 km (482 mi)
24. Po – 682 km (424 mi)
25. Glomma – 604 km (375 mi)
26. Maritsa – 480 km (298 mi)
27. Vardar – 388 km (241 mi)
28. Shannon – 386 km (240 mi)

Lakes and inland seas

  • Lake Constance (Austria, Germany, Switzerland; Bodensee)
  • Dojran Lake (Republic of Macedonia and Greece)
  • Lake Geneva (France, Switzerland; Lac Léman or Lac de Genève)
  • Lake Lugano (Switzerland, Italy)
  • Lake Maggiore (Switzerland, Italy; Lago Maggiore)
  • Lake Neusiedl (Neusiedler See)/Fertő (Austria, Hungary)
  • Lake Ohrid (Albania, Republic of Macedonia)
  • Lake Peipsi-Pihkva (Estonia, Russia)
  • Lake Great Prespa (Albania, Republic of Macedonia, Greece)
  • Lake Small Prespa (Albania, Greece)
  • Lake Skadar (Montenegro, Albania)
  • Lake Vištytis (Lithuania, Russia)
  • Lago di Lei (an artificial lake created by a dam; the waters are mostly in Italy but the dam is in Switzerland).

Major islands

Iceland, Faroe Islands, Great Britain, Ireland, the rest of the British Isles, Balearic Islands, Corsica, Sardinia, Sicily, Malta, Ionian Islands, Crete, Aegean Islands, Åland Islands, Gotland, Saaremaa, Svalbard, Hinnøya, Senja, Zealand, Fyn and North Jutlandic Island.

Plains and lowlands

  • East European Plain, the largest landscape feature of Europe
  • Northern European Lowlands
  • Pannonian plain
  • Meseta Central is a high plain (plateau) in central Spain (occupies roughly 40% of the country)
  • Po Valley, also known as Padan Plain, between Alps and Apennines

Temperature and precipitation

The high mountainous areas of Europe are colder and have higher precipitation than lower areas, as is true of mountainous areas in general. Europe has less precipitation in the east than in central and Western Europe. The temperature difference between summer and winter gradually increases from coastal northwest Europe to southeast inland Europe, ranging from Ireland, with a temperature difference of only 10 °C from the warmest to the coldest month, to the area north of the Caspian Sea, with a temperature difference of 40 °C. January average range from 13°C in Southern Greece to -20°C in northeastern part of European Russia.

Western Europe and parts of Central Europe generally fall into the temperate maritime climate, the southern part is mostly a Mediterranean climate, the north-central part and east into central Russia is mostly a humid continental climate  and the northern part of the continent is a subarctic climate. In the extreme northern part (northernmost Russia; Svalbard), bordering the Arctic Ocean, is tundra climate. Mountain ranges, such as the Alps and the Carpathian mountains, have a highland climate with large variations according to altitude and latitude.

-Enjoy the following exercises about the physical relief of Europe!


About The Earth

The third planet from the Sun is your home. The Earth is the only known planet where life can survive. As far as we know, there is no other planet in the universe like Earth. We have a very narrow temperature range that allows water to remain a liquid. Life has developed over millions of years because of that liquid. What else makes us special? We have an atmosphere made up of nitrogen, a relatively inert gas. If we had clouds of sulfuric acid or methane, life may never have developed.

The Plates

There are also huge landmasses on our planet. The rock plates that float across the surface are called tectonic plates. Those plates float on the mantle. The mantle is an area between the core and the crust. That mantle is basically filled with molten rock. It is kept in a liquid state because of the energy given off by the center (core) of the Earth. Scientists have also discovered that the pressure increases as you move towards the center of the planet. The core of the Earth has extreme temperatures and pressures that keep the iron and metals liquid and flowing.

And A Liquid In The Core

The flowing metal in our planet helps create something called a dynamo effect. Dynamos create large magnetic fields. In the case of the Earth, the magnetic field protects our planet from space. The region of magnetic protection is called the magnetosphere and protects us from the solar winds and solar radiation. You can see where solar winds and the magnetosphere collide in the aurora borealis

Breaking Apart The Structure

 The structure of the planet is fairly simple to understand. Just as the atmosphere has layers, the upper layers of the Earth have layers. If you look at the outside of the planet, you can see that about 65% of the planet is covered by oceans of water. The rest of the 35% of the surface is made up of the continents.

Ocean Zones

Let’s look at the ocean zone first. Scientists break the floor of the ocean into three basic levels. The abyssal plain is the deep ocean floor. The mid-oceanic ridge is the middle layer. The final division is the ocean trench. The trench is the deepest part of the surface of the planet. Maybe you have already heard that the distance from the floor of the ocean to the top of a volcano in Hawaii is higher than any mountain above the surface. If you hadn’t heard, now you have. Cool! On the edges of the oceans are the continental slopes. They are the fringes of the continental plates.

Zones of Land

Chances are, you’re on land right now. Scientists would say you are living on the sial. The sial is the part of the crust that is above water. It’s a continental plate floating over the globe. Right underneath the sial is the sima. The sima is the layer of the Earth’s crust that covers the entire planet. The sial is different in that it can begin and end where the plates do. You can think of the sima as the ocean floors. Under the sima is the mantle. When you consider the mantle is when you really start talking about the inner workings of the planet.

When you learn the layers of the Earth there really isn’t a lot to explain. It’s one of those memorization things. You might be wondering how all the layers came to be. When the Earth was forming billions of years ago, the matter came together. The densest matter moved to the center of the planet. The lighter rocks remained on the surface. When everything was done, the mantle wound up being about 2/3 the mass of the planet.

- Lithosphere (Sial and Sima)
- Asthenosphere (Molten Rock River)
- Mesosphere
OUTER CORE (Liquid Iron and Nickel)
INNER CORE (Solid Iron Compounds)

Plates Are Moving Beneath You

The basic idea behind plate tectonics is that there are eight major plates on the surface of the Earth. There are also bunches of minor plates. The plates are like the skin of the planet. They constantly move around the planet. When we say constantly moving, we’re talking centimeters each year. You couldn’t sit down and watch it happen. Or can you? You could watch it happen if you watched an earthquake.

They Really Float?

These plates make up the top layer of the Earth called the lithosphere. Directly under that layer is the asthenosphere. It’s a flowing area of molten rock. There is constant heat and radiation given off from the center of the Earth. That energy is what constantly heats the rocks and melts them. The tectonic plates are floating on top of the molten rock and moving around the planet. Think of it as ice floating at the top of your soda. When the continents and plates move it’s called continental drift. 

Think of the molten rock in the asthenosphere, not as rock, but as a liquid. It has currents and it flows just like any other liquid. When the floating plates spread apart, it’s called a spreading center. When they are moving together, it’s called a subduction zone. When they are forced together, it is called a zone of convergence. One of the plates usually moves under the other in a zone of convergence. As the plate moves down into the asthenosphere it begins to melt. The place where they meet has a crack or a trench. Some of the deepest parts of the oceans are these trenches.

Scientific Evidence

 How do we back up these ideas? Scientists have traveled all over the Earth and found evidence that supports the ideas of plate tectonics. First, they looked at the continents. Ever notice how Africa and South America look like they could fit together? Scientists did. They cut up a map, moved the continents close together, and came up with a huge landmass called Pangaea (one super-continent).

Scientists also looked at the fossils (long-dead animal bones and plants) on the different continents. They found that fossils on Australia were similar to the ones in Southern Asia. They think the same plants once lived on the continents, but when they split apart, new plants developed. When they were digging, they also looked at the types of rocks. The West Coast of Africa has very similar rock formations to those on the East Coast of South America. They are too similar to be a coincidence. 

When The Ground Moves

 Rumble rumble rumble! Have you ever been in an earthquake? Some people go through them all the time. In California there are dozens every day but they are usually very small. You tend to remember the big ones. Earthquakes are the breaking and cracking of the rocks inside the continental plates. The breaks happen after stress has built up in the surrounding area. There are usually very few or no quakes when the plates move slowly. When there is a fast movement of the plate, there is a snap (like breaking a cracker).

Changing The Landscape

 More than buildings collapse when an earthquake hits. The land itself is totally changed. You can see scars across the landscape. Those scars appear when one block of land has moved compared to another. Roads often change their placement. They either become uneven or just crack. Streams can also change course. Sometimes rocks can fall and block the stream. Other times, the land is even lowered in certain areas. When it’s lower, it’s easier for the water to flow in the new direction.

Changes also happen on larger scales. Fault valleys and troughs can be created. These areas have large amounts of fracturing (the fracture zone is large). After the land has opened up, weather begins to act on the area and erosion follows. Slowly, new valleys are created.

Waves Across The Land

You might think, “If it only happens in one place, why can you feel them hundreds of miles away?” The crack happens where the quake starts. Ripples then move out in waves across the plate. Those waves are called seismic waves. Those waves shake everyone up within a specific area. 

When scientists analyze an earthquake they look at several parts. They find out where the focus is. The focus is the exact point where the earthquake started. It is usually many miles/kilometers below the surface of the Earth. Scientists also look to see where the epicenter was. The epicenter is the point on the surface directly above the focus. When you think about the epicenter, try to remember there is actually a crack in the crust many kilometers below.

Built For Quakes

After an earthquake, you can turn on the television and see all sorts of footage showing buildings that didn’t quite survive. Buildings are built for up and down forces. If you jump on your floor a bunch of times your house will stay up. Earthquakes have forces that move side to side. Houses aren’t built for that direction of energy. When the Earth moves side to side, the house can’t wobble and it snaps. The walls collapse and roof falls in. Really tall skyscrapers are well designed for earthquakes. They are built to withstand strong winds. When strong winds happen, they can move side to side and sway if needed.

Look up in the Sky

What is the sky? What is air? What is the atmosphere? The atmosphere is just a thin layer of gases that surrounds the Earth. It can act many different ways and you need it to survive. Just as there are layers inside the Earth, there are also layers in the atmosphere. The layers interact, heat up, and interact with the top layer of the Earth’s crust. Sometimes you feel the atmosphere as a cool breeze. Sometimes it’s a really hot and humid day that seems to push on you from all sides.

Like an Envelope

If compared to the diameter of the Earth, the atmosphere is very thin. It is a coating of gases that protects the Earth and life on Earth from the vacuum and radiation of space. The thickness of the atmosphere is a balance between the gravity of the Earth and energetic molecules that want to rise and move towards space. The molecules become excited as energy from the Sun hits the Earth. If the Earth were much larger, the atmosphere would be thicker. The gravity of a larger planet would pull those gas molecules closer to the surface and pressure would increase. 

The atmosphere is far more than just a layer of gases surrounding the Earth. It is a moving source of life for every creature of the planet. While the atmosphere is mainly composed of nitrogen (N2), it also contains gases such as oxygen (O2) and carbon dioxide (CO2) that plants and animals need to survive. It has specialized molecules like ozone (O3) that filter out harmful radiation from space. The atmosphere also protects us from the vacuum of space. Without the atmosphere, our world would be as barren and dead as the Moon or Mercury.

Creating Climates

One result of the circulation of gases and particles is the climate of the planet. There is not one climate for the whole planet. Specialized climates are found in areas all over the planet. There is one type of climate over the equatorial Pacific Ocean and another type at the North Pole. The common trait of all of these Earth climates is the atmosphere.

The hot air from the equator eventually moves north or south to other climates. That warmer air combines with cooler air and mixing begins (and storms form). That constant mixing of the atmosphere helps to keep a stable system for the organisms of this planet to survive. Oxygen will never run out in one area of the planet, and the temperature will not skyrocket in another. 

A Cozy Blanket Around The Earth

The atmosphere looks like a blanket of gas when you look at it from space or the ground. When scientists started to examine the atmosphere, they noticed that there were different parts and different layers. There are layers of different molecules, temperatures, and pressures. Overall, the atmosphere is made up of a few main molecules. The air above you is made of 78% nitrogen (N2), 21% oxygen (O2), 0.9% argon (Ar) and 0.04% carbon dioxide (CO2). That’s it. The rest of it is made of things called trace elements. Those trace elements include water vapor, ozone, and other particles and molecules floating around.


The thermosphere is the layer closest to space. There is a huge amount of energy in this layer. The source of that energy is the solar radiation from space hitting the thermosphere. There are very high temperatures because of all the excited atoms zipping around. Something interesting you should know is that even though the temperature is very high (very excited atoms), there is actually very little heat.

Heat happens when energy is transferred from one atom to another. In the thermosphere there is such a low pressure (the molecules are spread out) that there is very little heat transfer. The mesosphere is directly under the thermosphere. The mesosphere has a lower temperature and is the coldest of all the layers in the entire atmosphere.


 The next layer down is the stratosphere. This is a layer with a very large temperature change. It changes from cold to warm, almost to 0 degrees Celsius (which is warm for the atmosphere).

The real importance of the stratosphere is the ozone layer. Scientists call it the ozonosphere. Those ozone (O3) molecules absorb large amount of UV (ultra-violet) radiation from the Sun. A chemical reaction takes place when an ozone molecule absorbs the UV radiation. The energy is then radiated as IR (infra-red) radiation, and that is what heats up the layer. Without the ozone, UV light would flood the surface of the Earth and the temperature of the stratosphere would be much cooler.


At the bottom of the atmosphere, where most of the life on the surface exists, is the troposphere. The troposphere is the only atmospheric layer that can support life. The higher layers have filtered out the harmful radiation, and there are large amounts of water vapor.

This is the layer where clouds develop, birds fly, and pollution collects. Yes, the troposphere is where humans most pollute the atmosphere. It’s right where we live. The pollution goes into the troposphere and rarely leaves until it falls to the ground or is mixed into the oceans. Some pollutants called CFC’s make it into the stratosphere and break down the ozone layer. 

Atmospheric Circulation

There are both global and local circulations of the air around us. Scientists have different terms for the circulation based on how large the air movements are. They say macroscale to describe wind currents that are on a global scale. Mesoscale describes storms like thunderstorms or blizzards. There are also winds and small circulations that only last for a few seconds. These smaller circulations are described with the term microscale.

Around The Neighborhood

 Let’s talk about local winds first. Sometimes you’re outside of your house and you feel a breeze. There are very fast winds high in the atmosphere, sometimes moving at hundreds of miles per hour. The unequal heating of air masses creates those winds. Those air masses are actually a big chunk of warm air and a big chunk of cold air.

The unequal heating and temperature differences also create a pressure difference, and the warmer gases spread out because the molecules need more room. All of these differences cause the molecules of air to move from one area to another. That air movement is the wind. When you open a soda can you are hearing wind coming out (so to speak). The gas rushes out because of the difference in pressure.

Around The World

Let’s look at the larger winds of the Earth called global winds. What about the huge, monstrous winds that circle the globe? What about the trade winds that helped sailors cross the Atlantic and Pacific Oceans? Scientists use the term cells. There are enormous cells of wind that wrap around the Earth. The winds that blow in the cells are created by temperature and pressure differences but also because of the spin of the Earth. The effect of the spinning Earth is called the Coriolis Force

Building Cells

A big part of circulation is due to temperature differences. Think about the Earth. It is warmer in the middle than on the top and bottom. The poles are colder than the equator. When warm winds want to move north, the cold winds need to move south and fill the empty space. Can you picture the cell being built? It’s a big rotation of the gas molecules in the atmosphere.

Greenhouse Effect – What Is It?

So you’re thinking its nice, comfortable and smells good in a greenhouse. It’s hundreds of happy plants and a bit humid. Don’t start thinking that the greenhouse effect for Earth would make such a nice place. It’s a term that scientists use to describe a slow increase in atmospheric temperature. That increase could be natural or accelerated by humans. It’s not always bad, but it does bring change. As with everything on Earth, there are cycles. Cold periods changing to warmer periods just happen in nature. For our discussion, the current greenhouse effect is changing the world we live in and it might not lead to happy plant times. 

It Just Happens

As we mentioned, many things cause the greenhouse effect in our atmosphere. Our story starts with energy from the Sun. High energy radiation hits the Earth and the shorter (more energetic) wavelength energy makes it to the surface. As all of that electromagnetic radiation hits the surface, the land and water heat up. When something heats up, it means they are releasing long wavelength radiation (infrared). When that new form of energy is radiated, it all doesn’t leave the Earth. Most of it bounces around our atmosphere. The result is an increase in the atmospheric temperature.

Water vapor also plays a part in trapping that reflected heat energy. More water vapor in the atmosphere allows for more absorption. With that said, think about the larger picture of the planet. As water vapor levels increase, the temperature rises. As the temperature rises, the polar ice caps begin to melt. A portion of that additional water moves to the atmosphere and allows for more absorption. The higher temperatures also lead to more extreme weather including winter storms and tropical cyclones.

All of that natural absorption, radiation, and reflection is supposed to happen. Without it, the temperature of our atmosphere would be much lower and life would have a harder time surviving. But lately, that temperature has begun to increase. and only part of it is natural.

Human Influence

 As with everything on our planet, we affect the environment. Related to the greenhouse effect, we are releasing many chemical compounds into the atmosphere that trap that longer wavelength energy (heat). When it is trapped and reflected back, the temperature increases. Fossil fuels are the easy culprit. All of our cars and power plants are spitting out emissions that spread through the atmosphere changing the way the Earth works. There are also many pollutants that are released into the air. It doesn’t happen as much in developed countries because of laws that are in place. Developing nations across the world need to generate income, so they often don’t think about the pollution. The problem is that the atmosphere of the world is shared and all of their pollution becomes our pollution after a few weeks. Chemical compounds such as carbon dioxide, methane, and ozone are big players in the greenhouse effect.

Other Planets

Astronomers studying our solar system believe that many other planets show signs of the greenhouse effect. Planets such as Venus have many gases in the atmosphere that permanently trap energy received from the Sun, further increasing their temperatures. If it can happen in our solar system, there is also reason to believe we will discover planets in other systems that show the same activity.

Flowing Water

 Welcome to something we like to call the hydrosphere! This is where we talk about the way water moves through the world. Water affects everything that happens in life. In Latin, “hydro” means water. Therefore, anything that scientists describe, when it comes to water, is a part of the HYDROsphere. That water may be at the bottom of the ocean or in the top layers of the atmosphere; it is all a part of the hydrosphere.

Water Water Everywhere

Water is in the air, on the land, between the rocks, and in every living thing. Water, in its purest form, is H20 (two hydrogen atoms and one oxygen atom). You will usually find ions or compounds floating around in it, but water is just one small molecule. As you’ll discover, it’s very busy. While water may move and carry other substances with it, you need to remember that pure liquid water is the thing that makes life on Earth possible. 

Liquid water makes the Earth a special place. Our planet has a very nice temperature range that allows water to remain in its liquid state. If we were a colder object like Pluto, it would not matter how much water there was on the planet; it would all be frozen. On the other hand, if we were on a very hot planet, all of the water would be in a gaseous state. Water vapor and solid water are useless to the living organisms found on Earth. Since the hydrosphere includes all of the water on the planet, you will study all of the various states of water. There will be solids in the deep glaciers, liquids of the oceans, and the vapor state of clouds.

I Am Water, Hear Me Evaporate

So you’re a water molecule. Chances are you’ll stay a water molecule and won’t ever be broken down. The world likes to keep its water around. Imagine that you’re moving through the hydrologic cycle. You evaporate, fall as rain, and drain into a river. There’s not a lot of excitement. How much time does it take? Scientists think that if you are lucky enough to evaporate into a cloud, you spend about ten days floating around the atmosphere. If you’re unlucky enough to be at the bottom of the ocean or stuck in a glacier, you might spend tens of thousands of years without moving.

Where is Groundwater?

Groundwater is water that is under the ground. Okay. You’re done with the tutorial. If you want more, you should know that groundwater is extremely important. Civilization gets most of its water from groundwater sources. There is more groundwater under the surface of the Earth than in all the lakes and streams put together. Unfortunately, groundwater is also polluted more than any other source of fresh water.

How It Gets There

Groundwater starts life on the surface. When it rains and the water moves through the soil, it’s called infiltration. The area near the surface of the soil is called the zone of aeration. There are spaces between the dirt and rocks that allow the water to flow through easily. Eventually the water makes it to rocks where scientists say it percolates deeper into the Earth (yes, like a coffee pot). The area where the water winds up is called the zone of saturation. Different from the soil, the zone of saturation has very small spaces between the rocks. The spaces are so small they may even be the size of large molecules. 

When the water can go no deeper, it creates an aquifer. An aquifer is an underground reservoir inside the rocks. When a farmer digs a well, they are digging into an underground aquifer. After they drill to the water table (the highest level of the aquifer), they are able to pump the water to the surface. As farmers pump too much water out of an aquifer, they find that the water table dips in that specific area. That dip in the water table is called a cone of depression.


We’re talking about humans pumping water out of an aquifer. There are two kinds of aquifers. One type you need to pump the water out of and another type in which the water is under pressure and moves towards the surface by itself. The pumping type is called unconfined. It has a layer of permeable (water can pass through) rock on top and nonpermeable (nothing can pass through) rock on the bottom. The water does not build up any pressure because it can expand and contract. The second type of aquifer is confined and called pressurized. It is sandwiched between two nonpermeable layers of rock. There is nowhere for the water to go when new water comes in and the pressure builds. The water eventually pushes up to the surface and creates springs and a type of freshwater called artesian water.

Freshwater Biomes

Let’s start with standing freshwater biomes, from a river to a lake or pond. The water doesn’t move very quickly here. It gives animals a chance to grow up. You’ll find larger fish, insects, and plants in this lake. Scientists divide lakes into two major levels, limnetic (the top), and profundal (the deeper part). They even have names for the shore (littoral) and the very bottom on the floor of the lake (benthic). You’ll find most of the activity in the limnetic zone. Fishermen often fish in the limnetic zone.

Salty And Fresh Water Mixing

Estuaries are the regions where the freshwater meets the saltwater. They will always be found near the coast. Fresh and saltwater mix constantly in estuaries. This mixing allows huge amounts of marine life to exist. It turns out that this is a great area for fish to lay their eggs. The water is quiet and still and when the fish are tiny, they can hide in the cloudy (brackish) water. When you look around you will see all sorts of birds such as cranes and storks and insects who lay their eggs near the still water also.

Right Around The Coasts

The intertidal zone is where the waves hit the coast. Tides are controlled by the gravity of the Moon. The Moon causes them to move up and down each day. As they rise and fall they leave a patch of coast under the water when the tide is high. The same area is dry and exposed when the tide lowers. It’s usually very rocky here with lots of algae and small creatures. You can walk around when the tide is low and find sea urchins, sea stars, and all sorts of birds and insects looking for food with you.

Next to the intertidal zones are subtidal zones. This zone is always under water along the coasts of continents. You can find coral reefs and most of the world’s fish in this region. You’ll also find larger fish because they have more room to swim and more little fish to eat. There are also huge sandy plains in this subtidal region. Because of all of the waves and activity, there is a lot of oxygen in the water to support the wildlife.

Deep In The Ocean

There comes a point where the floor of the ocean just drops away. Now you are in the deep ocean biome. Scientists break this biome into three layers. At the surface is the euophotic zone. There is a large amount of sunlight and oxygen but very few nutrients. They all fall to the bottom of the ocean. You’ll find many small organisms that are photosynthetic. As we move down, we get to the bathyal zone. The light is very dim. No little organisms are found here, just some fish who feed on the organisms at the surface. At the bottom of the ocean is the abyssal zone. This zone is pitch black, with no producers, little oxygen, extremely cold, and high pressure. There are living organisms down there. They usually feed on the dead stuff that falls from the surface layers. Then, of course, there are the predators that swim through the murky depths.

A Big Ball of Life

The biosphere is all about life. Physical geographers use the term biosphere to describe our living world. This is where all of the trees, bugs, and animals live. The biosphere extends to the upper areas of the atmosphere where birds and insects can be found. It also reaches deep into the ground at a dark cave or to the bottom of the ocean at hydrothermal vents. The biosphere extends to any place that life (of any kind) can exist on Earth.

The biosphere is the one place where all of the other spheres of the planet work together. Think about the interactions for a second. The land interacts with the water (hydrosphere). The land interacts with the air (atmosphere and climates). The land even interacts with forces deep inside the Earth and the energy coming to the Earth from space. All of those forces work together to create our living world.

Big, Small, and the Smallest Factors

Many factors affect the biosphere and our life here on Earth. There are large factors such as the distance between the Earth and the Sun. If our planet were closer to the Sun, it might be too hot to support life. If we were further away, it might be too cold. Even the tilt of the Earth is important. Seasons and seasonal climate changes are direct results of the tilt of the Earth towards or away from the Sun. 

 Smaller factors are also act on the biosphere. If you were to look at a piece of land that was only one square mile, you would find influential factors such as climate, daily weather, and erosion. These smaller factors change the land and the organisms must react accordingly. Even though humans are able to control their environment, they are still vulnerable to weather and earthquakes.

The smallest of factors in the biosphere work on a molecular level. Chemical erosion is a great example of a landscape changing one molecule at a time. Oxidation and reduction reactions happen all the time, changing the composition of rocks and organic materials. It’s not just chemistry at work on the molecular level. Tiny organisms such as bacteria and single-celled organisms are constantly working to break down materials (organic and inorganic) and change the world.

An Ecological System

 The word ecosystem is short for ecological systems. An ecosystem includes all of the living organisms in a specific area. These systems are the plants and animals interacting with their non-living environments (weather, Earth, Sun, soil, atmosphere). An ecosystem’s development depends on the energy that moves in and out of that system. As far as the boundaries of an ecosystem, it depends upon how you use the term. You could have an entire ecosystem underneath a big rock. On the other hand, you could be talking about the overall ecosystem of the entire planet (biosphere).

An ecosystem can be as small as a puddle or as large as the Pacific Ocean. That ecosystem includes every living and non-living thing in the area. It is several small communities interacting with each other.

Let’s look at a puddle example. You might start by looking at the temperature, depth, turbulence, sunlight, atmospheric pressure, weather patterns, wind, nutrients, etc. Those are just the non-living things in the ecosystem of a puddle. When you add on all the living interactions, you have a good idea how complex an ecosystem can be. Even a puddle is an amazing place.


Scientists discuss some general ecosystem types. They call them biomes. A biome is a large area on the Earth’s surface that is defined by the types of animals and plants living there. A biome can be partially defined by the local climate patterns. You may also have more than one type of biome within a larger climate zone. Here is a short list of possible biomes.

- Tropical Rainforest (Think about Brazil)
- Tropical Savanna (Think about Africa)
- Desert (Think about the middle east)
- Mediterranean Woodland (Think about coniferous forests)
- Mid-latitude Grassland (Think about Oklahoma)
- Mid-latitude Deciduous Forest (Think about the east coast of North America)
- Tundra (Think about frozen plains of Alaska)
- Ice Caps (Think about the poles)


Biomes don’t just start and stop when they border each other. They all have transition zones that have characteristics of both sides. That zone is like a blending of two biomes. Scientists call it an ecotone. Ecotones can happen at the edges of forests, deserts, and mountain ranges. They are often easy to see because one type of world (many trees) changes quickly into another type (the cliffs of a mountain). While an ecotone on the ground may not cover a large area of land, climate transition zones between biomes are often very large.

Another Link in the Food Chain

 Everyone plays a specific role in the food chain of life. You might be a human thinking they are king of the hill or you might be a bacterium under the feet. You are very important to the survival of the system no matter what role you play.

As you study more about ecosystems and cycles in life, you will see the terms food chains and food webs. They describe the same series of events that happen when one organism consumes another to survive. Food web is a more accurate term since every organism is involved with several other organisms. Cows might be food for humans, bacteria, or flies. Each of those flies might be connected to frogs, microbes, or spiders. There are dozens of connections for every organism. When you draw all of those connecting lines, you get a web-like shape.

The Producers

Producers are the beginning of a simple food chain. Producers are plants and vegetables. Plants are at the beginning of every food chain that involves the Sun. All energy comes from the Sun and plants are the ones who make food with that energy. They use the process of photosynthesis. Plants also make loads of other nutrients for other organisms to eat.

There are also photosynthetic protists that start food chains. You might find them floating on the surface of the ocean acting as food for small unicellular animals.

The Consumers

Consumers are the next link in a food chain. There are three levels of consumers. The levels start with the organisms that eat plants. Scientists named this first group of organisms the primary consumers. They are also called herbivores. They are the plant eaters of the chain. It might be a squirrel or it might be an elk. It will be out there eating plants and fruits. It will not eat animals.

Secondary consumers eat the primary consumers. A mouse might be a primary consumer and a cat might be the secondary. Secondary consumers are also called carnivores. Carnivore means “meat eater.”

In some ecosystems, there is a third level of consumer called the tertiary consumer (that means third level). These are consumers that eat the secondary and primary consumers. A tertiary consumer could be a wolf that eats the cat and the mouse.

There are also consumers called omnivores. Omnivores can either be secondary or tertiary consumers. Humans and bears are considered omnivores: we eat meat, plants, and just about anything.

The Decomposers

The last links in the chain are the decomposers. If you die, they eat you. If you poop, they eat that. If you lose a leaf, they eat it. Whenever something that was alive dies, the decomposers get it. Decomposers break down nutrients in the dead “stuff” and return it to the soil. The producers can then use the nutrients and elements once it’s in the soil. The decomposers complete the system, returning essential molecules to the producers.

Break It Down

 Erosion is the process that breaks things down. As far as we’re concerned, erosion is the breakdown of the continents and the land around you. The overall effect of breaking down and weathering the land is called denudation. Denudation is the process of erosion. In nature, large things are broken down into smaller things. Boulders become sand. Mountains are rained on and become hills. The pieces of the mountain become smaller pieces and go down the sides of hills. Weathering and erosion always happen in a downhill direction.

Erosion is an easy idea to understand. If you see a rock, pull it out of a mountain. Then throw it down on the ground. You are now a part of the erosion of that mountain. You have taken a big object (a mountain) and started to make little objects out of it (a rock). When that rock hit the ground, it could have cracked and made some tiny pieces of rock (sand). Erosion is just that easy. When it rains, the same process happens. Rocks are washed down a mountain or down a stream. Soils are washed away. The ocean beats against a cliff and breaks it apart. They are all examples of denudation. 

Things don’t just disappear. The masses of dirt and rock are moved to another form and place. Scientists call it mass wasting. The wasting is the loss of matter in one place.

Mass wasting can happen two ways:
1) mechanical, similar to breaking a rock with a hammer; and
2) chemical, similar to pouring acid on a rock to dissolve it.

A surefire way to tell what is happening is to check the color of the rock. If a boulder breaks because of frost, you won’t see a color change. If you see rock that has been near the ocean, you may observe color changes because it is oxidizing.

Does Erosion Build Things Up?

Erosion happens at the tops of mountains and under the soil. Water and chemicals get into the rocks and break them up through those mechanical and chemical forces. Erosion in one area can actually build up lower areas. Think about a mountain range and a river. As the mountain erodes, the river carries sediment downstream towards the ocean. That sediment slowly builds up and creates new wetlands at the mouth of the river. The swamps of Louisiana are good examples of sediment carried by the Mississippi River and collected at the end.

Natural Resources And Recycling

The Earth is a closed system. For our examples, we need to think that nothing comes in (except energy) and nothing goes out (except energy). Even the amount of energy that moves in and out of the Earth is equal. If more came in than was released, we would heat up. If the Earth gave off more energy than it received, we would cool down. The smarties in the crowd are saying “What about meteorites?” Yes. There are small amounts of matter hitting the Earth from space. On the other hand, we are sending more satellites and spacecraft into orbit. A little is being lost too. 

The big point of this section is to look at the idea that humans have a finite amount of material on this planet. We call these materials natural resources. Not only are humans using these materials, but nature is using them too. The difference between humans and nature is that nature doesn’t waste. Materials are cycled through the ecosystems of the Earth and reused whenever possible. There have been points in time where nature runs out of things and it adjusts, changing ecosystems or the types of organisms that survive. Think about water for a second. Many places used to have large freshwater lakes with thriving communities. Over thousands of years, those lakes dried up and some even became deserts. Nature didn’t just give up, with the change in environment, new organisms began to thrive and the ecosystem changed.

Humans may be doing that as we speak. We use natural resources, but don’t return them to the system. They may wind up in landfills or at the bottom of the ocean. If we have a finite amount of resources, there is always the possibility that we will run out. Nature will continue. The organisms that survive will change. But we might not be one of them. Don’t worry about it this afternoon. We have plenty of stuff for a long time.

In The Forests

Forests are an easy starting point. These are dense ecosystems with a large amount of plant life. Types include tropical and temperate forests. Some have a lot of rain and others have seasonal moisture. Humans like the land and the trees. Realtors say location-location-location when they talk about homes. They know that there is only a specific amount of space in an area that people can live. Unfortunately for forests, they are sometimes sacrificed for our needs.

We like the timber. We build houses and all sorts of stuff from wood. The big worry of many people is not timber, it’s the fact that many forests are being cut down to increase the amount of farmland. What happens when you lose forests? Well, there’s less timber. There’s also a complete change in the ecosystem. Forests absorb heat and cool areas. They also release oxygen into the atmosphere and help purify the air. When you clear-cut a forest the temperatures can increase, wind patterns can change, and (many would argue) it’s less beautiful. But there’s always a trade-off. We need more food. More farmland=more food. As with all of our discussions of natural resources, management of the resources is the key to success.

In The Mountains

Are they just big hunks of rock? No way. Mining operations see mountains as the source of their ore. They might be looking for iron, silver, gold, diamonds. whatever. All mining requires a hole in the mountain, blowing up part of the mountain, or maybe making a deep hole in the ground. We use the mountain loosely. Think of it as the surface of the Earth. As with forests, there are only so many areas with easy mining opportunities. If humans use up all of those locations, the cost of getting those resources will go up. There’s also the problem of destroying the surrounding area. Not only do some mining operations leave big holes in the Earth, but also the process of mining often collects toxic materials in the rocks. Those pollutants are left over and poison the surrounding area. There are ways to use these resources, but intelligent management is the key.

In The Water

Oceans, water, puddles. All areas with water are natural resources. The most direct connection to you is drinking water. Aquifers exist under the surface and wells pull that freshwater out for you. If humans take out more water than goes in, they will run out of water. An even worse situation would happen if the water were accidentally poisoned (maybe mining or farming). If you look at all of the water on Earth, there isn’t a lot of freshwater. That’s what makes it so important. Saltwater provides other things we need including food. Fishing is a huge industry that needs to be managed so we don’t over fish the oceans. If we do, there won’t be enough fish left for the world. We’ll say management again, but you need to understand there aren’t easy answers.

Real Competition

You might think of competition as a baseball game or maybe two wolves fighting over a piece of meat. The real competition of your future will come from people competing for natural resources. There will always be at least three groups involved. You will hear about business and companies that want to take as many natural resources as they can in order to have a more successful business. Many of them will not be thinking long term, especially in developing nations. You will also hear about environmental extremists who want to keep the Earth exactly as it is. They might want to lock out all industry from using any more natural resources. They often think that because they are willing to sacrifice certain pleasures in life, everyone should. And then there will be those in the middle. People who think long-term and want to preserve the environment but know that business will need some of the resources. The environmental managers will plan for plans such as reforestation and fisheries to replenish the oceans.

There will be no easy answers. Just know that when it comes to natural resources you need to think long-term. The Earth and nature will adjust. It’s the people that might not be happy with the results.

Climate Basics

First a definition… What the heck is a climate? Is it weather? Is it the rain? Is it a hot day in August? Yes, yes and yes, but only in one place at a time. Climate is the atmospheric condition in a certain location near the surface of the Earth. Is the Aurora Borealis (Northern lights) a climate? No. Is there such a thing as a global climate? Yes. Kind of. It’s all of the climates of the planet added up. If the Earth were getting hotter you would have to say, “All of the global climates are increasing in temperature.”

Climate Variety

There are many types of climates across the Earth. You live in one of them or one the border between two. Every year as the seasons change, your climate changes a bit. It might get warmer or colder. You might have more or less rain. You might have more or less sunlight that changes all of that other stuff.

Scientists have broken down the world’s climates into a few types:
- Polar: Ice Caps
- Polar: Tundra
- Subtropical: Dry Summer
- Subtropical: Dry Winter
- Subtropical: Humid
- Subtropical: Marine West Coast
- Subtropical: Mediterranean
- Subtropical: Wet
- Tropical: Monsoon
- Tropical: Savannah/Grasslands
- Tropical: Wet

What Makes A Climate?

Several factors go into making a climate. Those factors also affect what the climate will do. Scientists can then make observations and predictions of what will happen in certain climates. If it’s hot today and a storm is coming in, you can guess it will get cooler. More specifically, if it’s summer where you live, hot and humid, you might be able to guess that you’ll have thunderstorms in the evening. These factors usually happen in the atmosphere in the area you are looking at. There is more water vapor in the air if it is humid. If there is a lot of wind, something is making that wind speed up. It could be a series of mountains, or you could be near the ocean. 

As we move into these factors, you need to understand that they all affect each other. Examples would show you that higher temperatures might increase evaporation of water that would then increase humidity.


The temperature changes throughout the day. At mid-day the temperature gets hot, the land heats up, and air rises. In a coastal area when the air rises, it is replaced by cool air from the ocean. This creates a breeze. When evening comes, the ground cools and the air over the ocean is warmer. The breeze shifts to move towards the ocean.


Atmospheric pressure is another important factor. There are large masses of high and low pressure across the Earth. There are also small changes in air pressure that affect you locally. In the borders between high and low pressures you will find storm fronts or smaller changes in weather: temperature, humidity, or cloud cover.

Cloud Cover

The number of clouds and the amount of dust and smog affect local climates by changing the temperature. Increased cloud cover decreases the amount of energy hitting the Earth from the Sun. This decrease in energy lowers temperatures. In an extreme example, something called nuclear winter covers the entire planet with clouds. With no sunlight getting through, the plants begin to die.


Humidity is a measure of the water vapor in the surrounding air. As humidity increases, the chances of rain also increase. You see, the air can only hold so much water vapor before it says, “Whoa! I can’t do it anymore!” Then it needs to rain. Thunderclouds can be created and violent storms can dump huge amounts of water on the land.


Wind speed is that last factor we will cover. When we talked about temperature we discussed on-shore and off-shore winds. Sometimes these can be nice slow breezes and other times very fast and destructive. You may also encounter situations near the base of mountains where changes in temperature create winds that reach 80 miles per hour.


The most moist and warm of all the climates on the planet is the tropical rainforest climate. This climate experiences daily thunderstorms. The storms are called convectional because they are caused by the surface heating up during the day, and the high humidity creates thunderclouds. With the high amount of rain, the trees never lose their leaves. They are evergreen. The trees also have big broad leaves to catch the Sun’s light. The trees are very high and their branches create a canopy. That canopy lets very little light reach the ground, and there are very few plants on the surface. You will find bacteria and small animals on the ground that break down the plant material that falls. Go to Brazil to see these forests.

Marine West Coast

The marine west coast climate is characterized by a mild winter and a cool summer. Because these areas are so close to the ocean, the temperatures generally remain within specific ranges. Much of Europe is classified as this climate type. When you say mild, you have to consider the extremes of temperatures that can happen at the same latitudes. Even though you can expect a reasonable temperature range, there is always unpredictable weather (day-to-day occurrences). Sometimes you get a lot of fog, and other times you get a strong frost at the end of spring. Those frosts make the growing seasons shorter than for most other places.

Dry Summers

Mediterranean dry summer climates have very wet winters and dry summers. Maybe you’ve been to California or to places in Europe. Even though they are thousands of miles apart, they have very similar climates. They are kept cool (in summer) because of the ocean currents that move past their coastal areas. They get most of their rain for the year (70%) in the winter months. The rest of the year is generally very dry. In California the local plants are considered to be drought resistant because most of the water has gone by April and May. They have to survive until November when the rains begin again.

Getting Colder

The subarctic climate type is the last stretch of land before you get to the polar regions. Subarctic climates are more seasonal than many other climates. Because they are at such high latitudes, their day length also changes a lot (very short in winter, long in summer). Sometimes the Sun comes up at three in the morning! A characteristic of these areas is that they may have had glaciers on the land thousands of years ago. The glaciers cut through the landscape and even now, there are very few plants and very thin soil.

-To understand better this topic, enjoy the following activities and videos:’s+Structure.swf?f=print Planet Earth (Views From Space)





Astronomers still debate how the universe originally formed.Everything that exists, exists in the universe. Before you start getting into the details about things that happen in the universe, try to think about how big it is. Start with you. You are only a couple of feet long. Compare yourself to a whale, or a dinosaur. They are enormous. Then think about how big your city is and how much space you take up in your state, your country, or your continent. Then imagine the Earth. You’re not very big now. Hold on it gets worse.

The Earth is pretty small when you compare it to Jupiter. Jupiter is pretty small compared to the Sun. As you go on, there are millions of suns in our galaxy and thousands of galaxies in the universe. No one really knows how many. There are some scientists and mathematicians with theories, but nobody really knows.


Large objects have a greater gravity than smaller objects. Gravity or gravitational forces exist when one object attracts another. We’re not talking about finding someone really cutey-wootie, awwww! We’re talking about the molecules of one object pulling on the molecules of another object. It’s like the Earth pulling on you and keeping you on the ground. That’s gravity at work. Every object in the universe that has mass has a gravitational force. Even you exert gravity. When you compare your mass to the mass of the Earth, your gravitational force isn’t very impressive. Sorry about that.


Obviously gravity is very important on Earth. Other planets also affect our world. Our connection to the Moon’s gravity makes the tides rise and fall. The Earth’s gravity keeps our planet orbiting the Sun, just like the Sun’s gravity pulls on our planet. When the earth spins and gravity pulls on the clouds, weather can be affected. We have to bring up an important idea now. The Earth always has the same pull on every object. If you drop an acorn, or you drop a piano, they will fall at the same speed. It is the Earth’s gravity and pull that make objects speed up when they are falling. The Earth constantly pulls and objects constantly accelerate.


“People always say, “What about feathers? They fall so slowly.” Obviously, there is air all around us. When a feather falls, it falls slowly because the air is in the way. There is a lot of resistance and that makes the feather move slower. The forces at work are the same. If you dropped a feather in a container with no air (a vacuum), it would drop as fast as a baseball.


NASAs Spitzer, Hubble, and Chandra observatories see different wavelengths of light. We’ve already covered the universe. Let’s focus on something smaller, a galaxy. Right now, you’re sitting on a planet that orbits a star in the Milky Way galaxy. As you know, there are loads of galaxies in the universe. Each is different from the other, like fingerprints. We’re going to talk about a few of the common traits of galaxies and how you can look up in the sky and look for other galaxies.


Organized galaxies are made of millions of stars and systems. While we can’t take a picture of our galaxy, astronomers use a variety of telescopes to study nearby galaxies.


As astronomers have studied galaxies in detail, they have determined that there is more than dust, stars, and systems. They currently believe that about 90 percent of the matter in galaxies is called “dark matter.” Dark matter is matter that does not emit any radiation that can be detected using current instruments. We know that dark matter exists because of the gravity exerted on other objects. If you want to work on the cutting edge of astronomy, you might want to look into the study of dark matter and dark energy.


The Hubble telescope viewed the galaxy cluster Abell 2218 in 2003. We spoke about gravity earlier. We explained that gravity holds you to the Earth. Gravity holds the Earth in orbit around the Sun. Even other stars effect our Sun and pull it into the Milky Way galaxy. Now you need to think about the combined gravity of an entire galaxy. The gravity of one galaxy can pull on nearby galaxies and eventually form clusters of galaxies. Most of the gravity that attracts galaxies to each other comes from unseen particles called dark matter.



This is how the Milky Way would look like if seen from above. We live in the Milky Way galaxy. Based on our observations, we have a barred-spiral galaxy. While we can estimate the size of our galaxy, it’s a little harder to determine its age. We know that the Sun is about 5 billion years old. It’s a young star. Based on the observations of other stars in the Galaxy, we think that the Milky Way may be about 12-14 billion years old.

Our galaxy looks like a spiral form because stars and systems are grouped in constantly moving arms that spin around the center. The Solar System is about half way between the edge of the stellar bar and the edge of the galaxy.


We are definitely not alone in our galaxy. There may be as many as 400 billion stars and systems in the Milky Way. Our closest neighbor is Proxima Centauri. It is about 4.2 light years from Earth. Don’t forget that our entire galaxy is 100,000 light years across.

At this time, the Voyager spacecraft are the only manmade objects to leave the Solar System. Launched in 1977, they should reach the edge of the Solar System by 2015. At this pace, they will need to travel another 82 thousand years before reaching the closest star. As you can tell, we are moving pretty slowly right now and travel to another star is not likely in our lifetime.


Millions of galaxies are out there. Ours is impressive because it is ours. The closest galaxy to ours is called the Sagittarius Dwarf. It is a little over 78,000 light years away. If it would take us thousands of years to reach the closest star, you can only imagine how long it would take to reach the closest galaxy.

What about life out there? Most scientists believe that there is some form of life on another planet in the universe. With so many galaxies, systems, and planets, chances are good that we can something alive somewhere. Will we find super-smart aliens? Who knows. Most believe that there will be some form of life, maybe microscopic.


The Sun is the closest star to the Earth. It is about 93 million miles away. What is a galaxy without thousands of stars? A vacuum. Those thousands of stars grouped together form the galaxies you can see with a telescope. Stars are the objects that heat and light the planets in a system. Everything revolves around stars. Thousands of stars cover our galaxy and when you look at our star, the Sun, you will see it is quite small. Throughout the universe, there are big ones, small ones, and different colored ones. We’re going to discuss the way scientists study stars and how stars affect the planets that orbit them.


So you’re out one night and you look up into the sky. Assuming you aren’t in a city with tons of smog or clouds, you will probably see a sky filled with little dots of light. Those dots (this should not be a surprise) are stars. Some are only a few hundred light years away and some are thousands of light years away. They all have some things in common. You see, stars are huge balls of fire. They aren’t just any fire. That fire is from a constant number of nuclear reactions.


Not all stars have solar systems spinning around them. Some stars are just sitting out in the middle of nowhere. Some stars have a companion star nearby, kind of like a twin. When you have a twin, astronomers call you a binary star.

A star is a huge ball of plasma, usually made of hydrogen (H) and helium (He). That ball of fire also gives off light. All kinds of light. There are visible, infrared, ultraviolet, and X-rays constantly emitted into space. You may find planets that are almost identical to the makeup of stars, like Jupiter, but something has not ignited their nuclear reaction.


All stars require a spark of ignition to become stars. We emphasize the basics at Cosmos4Kids. You’re here to learn about what a star is and a little bit about them. Once again, a star is basically a ball of gas that has nuclear reactions occurring in its atmosphere. As those reactions occur, huge amounts of energy are released into space. The energy is released as electromagnetic radiation (EM). That EM radiation includes visible light, UV (ultraviolet) light, IR radiation (infrared), x-rays and gamma rays. There are also very small particles leaving the star. Those particles are byproducts of the nuclear reactions.


We have a yellow star. That’s the Sun. Some systems have red stars. Others have a blue tint. The color of a star depends on its surface temperature. Bluer stars have a higher surface temperature. Lower temperature stars give off a lot of red light.


Astronomers look at three main characteristics of stars. They study luminosity (brightness), temperature, and radius (size). Each of these three factors can tell you a lot about a star. Take our star for example, the Sun. As far as stars are concerned, it is rather small. The yellow color tells you it has a nice, medium temperature. The small radius also gives an indication that it not much of a powerhouse. Last is the luminosity. On Earth, the Sun may seem bright. Compared to other stars it is only a candle. Astronomers consider our Sun to be in the main sequence of its development.


This bow shock appeared near a young star in the Orion Nebula. Just like living organisms, stars have a life cycle. In the same way that you are born, develop, age and die, stars do the same things. One big difference is that stars don’t need parents. Stars are born from huge clouds of gas and dust. It’s amazing how that gas and dust are probably the most boring things in the universe and they can become everything, asteroids, planets and even stars. So you’ve got that huge cloud of dust and gas. Astronomers call that cloud a nebula. That’s when it all starts to happen.


That nebula starts to condense. Slowly but surely over millions of years, gas particles start to cling to each other, then they attract other particles and molecules. The nebula begins to condense and form a ball. That ball is called a protostar. “Proto” is a prefix that means “early” or “before.” So a protostar is the first step in becoming a full-fledged burning star.


After the star finished the protostar phase, it becomes even denser. The heavy elements move to the center of the star while the light gases stay in the star’s atmosphere. Those gases are usually hydrogen (H) and helium (He). Then something amazing happens, the nuclear fire begins. The star heats up and the gases ignite. This step in the development process is called the main sequence. If you looked, you would see the birth of the star.


In the Solar System section we speak a little about Jupiter. Jupiter is a special planet in that it has a very similar makeup to the Sun. It has a low density and hydrogen and helium are the main components of the atmosphere. It is still missing one thing, nuclear fire. Jupiter could be the star that never was.


The gravity of black holes is so strong that light is pulled in. Black holes are areas in space where there is a huge amount of mass in a very small space. The gravity of this mass is so great that everything in the area is pulled toward the mass. Even light, with its tiny mass, is pulled into the center of the hole. No object can escape the gravitational pull of a black hole.

Have we ever seen a black hole? No. Actually you can’t see a black hole because no light escapes the event. Astronomers use other ways to look for black holes. Since they have large masses and gravities, they affect the surrounding stars and systems. They have found evidence of black holes in the dark centers of galaxies and systems that emit large amounts of x-rays.


As systems develop, there are billions of possible planet types. A system is a star (or two) and a series of objects that revolve around that star. The objects could be gas giants like our Jupiter or small rocky planets like our Mercury. There may also be other non-planetary objects. You will probably find moons around the planets and asteroids/comets zipping around the star in highly elliptical orbits. Just as in biology, a system is made of many parts that all interact with each other.


We have a whole section on our system. Because the name of our star is “Sol”, we live in the Solar System. While there is a debate among astronomers, we currently have one star, eight planets, and several smaller “dwarf planets”. There are also several other large objects and an asteroid belt orbiting the Sun. Our system began to develop several billion years ago with a huge amount of dust and small objects. Over time, the star and planets developed.


As our technology improves, we are able to see further into the universe and study other stars. Seeing a star is pretty easy, they are bright dots in the sky. Seeing a planet is a lot harder. Since planets don’t give off light, we have a tough time seeing them. There are a few ways we detect other planets and possible systems. You might see a big planet because it is reflecting the light of its star.


We have only confirmed the existence of life on one planet. You can learn more about planets in the Solar System section but let’s give a quick overview that a planet is made up of heavy elements. Stars are mainly made of hydrogen (H) and helium (He). Planets generally have all of the other elements in their crust and core. You will find large amounts of iron (Fe) and minerals. Also, planets do not have the nuclear reactions igniting their atmosphere.


When you think about the characteristics that make a planet a planet, think about the Earth. We have an atmosphere that is not on fire. The Earth is basically a large rock. We have a core of molten iron and plates of rock floating on the surface. Also, most of our mass and diameter are because of the planet, not the atmosphere. Mars and Venus are the same way.

But what about Jupiter, what makes it a planet? It has huge atmosphere compared to the size of the planet. Remember, that there are no nuclear reactions in the atmosphere of the planet. Therefore, Jupiter is a planet. If you go deep enough, you will find rock that exists in the center of that huge, gaseous atmosphere.


As you know, we have completed several missions that study other planets. Even today, engineers across the Earth are developing new spacecraft that will explore our Solar System. Since spacecraft are relatively small, scientists debate the number and types of instruments that will visit each planet. They prioritize mission goals. Some spacecraft focus on studying atmospheres and gases. Other spacecraft are detecting radiation and gravitational fields. If you are interested in space, there are millions of things to discover in our Solar System.


While we are studying the planets in our Solar System, some astronomers are using a variety of telescopes to discover planets in other systems. As of summer 2006, 193 planets have been discovered in other systems. Many of those planets are large gas giants similar to Jupiter. The bigger they are, the easier they are to find.


In a lunar eclipse, the Earth moves between the Sun and the Moon. Eclipses are events that happen when one planet or moon is lined up between a star and another planet or moon. For example, you will see an eclipse when the Earth passes directly between our Sun and the Moon. An eclipse could also happen on the surface of Mars when one of Mars’ moons passes between the surface and the Sun. It’s all about blocking light and creating a shadow.


We’ve been talking about planets passing between the Sun and another object. A lunar eclipse happens when the Earth passes between the Sun and the Moon. Lunar eclipses can only happen when there is a full moon. As the Moon’s orbit takes it behind the Earth, a shadow crosses the face of the full Moon. The shadow does not always cover the entire Moon in a total eclipse. There are also partial and penumbral lunar eclipses. There are two or three lunar eclipses each year. The best pictures come from a total lunar eclipse. If you hear about a lunar eclipse, feel free to look up. They are safe to look at.

In a solar eclipse, the moon moves between the Sun and the Earth.


Solar eclipses are more spectacular than lunar eclipses, but much more dangerous for your eyes. Never look directly at a solar eclipse (or the Sun for that matter). Solar eclipses happen when the Moon passes between the Sun and the Earth. The Moon casts a shadow over a portion of the planet, leaving that area in darkness. If you were watching from space, you could see the shadow pass over the surface. You would also notice that the Moon’s shadow only covers a part of the planet because the Earth is much larger than the Moon. A lunar eclipse can put the entire surface of the Moon in darkness.

There are one or two solar eclipses each year. The shadow moves across different areas of the planet. Depending on the location of the Moon, there are total and annular eclipses. A total solar eclipse happens when the Moon blocks the entire Sun. An annular eclipse only covers some of the Sun. A little ring of the Sun can be seen around the Moon. There are different eclipses because the Moon can be closer or further away from the surface of the Earth.


A variety of planet types orbit the Sun in our solar system. Our system of one star and eight planets was born about 4.6 billion years ago. All of the pieces were created at the same time. But wait! It wasn’t a big “POOF!” and everything was here. It took billions of years for the entire system to develop. All of the gases, dust, and pieces of the system were around at the start. Eventually a star, eight planets, some smaller dwarf planets (like Pluto), and an asteroid belt developed. There wasn’t even a star when the Solar System started out.


The system began as a spinning blob of gases. As the blob spun for millions and millions of years, it began to flatten. It probably looked like that shape for a flying saucer. It was a round, flattened disk with a bulge in the middle. That bulge was the beginning of the Sun. Scientists call that “baby” sun a protosun. The last step for the Sun was the magic that ignited it and caused it to shine. Do you remember that dust and gas swirling around that didn’t become the Sun? The disk flattened even more and the planets began to develop.


Eight planets developed and now orbit the Sun. As you move away from the Sun, you will first find four planets, then a group of small asteroids, and four large Jovian planets. There are also objects called dwarf planets that include bodies such as Pluto and Charon. In the past few years, astronomers have started to discover smaller objects beyond Pluto in the Kuiper Belt. The distance from the Sun to the Earth is considered “1″ (scientists call that distance an astronomical unit).The average distance to Pluto from the Sun is 39.5. The Voyager probes launched decades ago are just now reaching the outer edges of our Solar System. That edge, called the heliopause, is far beyond the orbit of Pluto.


As the planets developed, two types began to emerge. In our system, we have planets that are mainly made of rock and those that are mainly made of gases. The official names are terrestrial (rocklike) and Jovian (those with gases). Of the eight planets in our system, Mercury, Venus, Earth, and Mars are the terrestrial planets. The Jovian planets include Jupiter, Saturn, Uranus, and Neptune. The Jovian planets are all much larger and have a lower density when compared to terrestrial planets. Astronomers have recently decided that there are objects in the Universe that are larger that asteroids and comets, but smaller than real planets. These dwarf planets also orbit the Sun and include Pluto, Charon, and others discovered in the Kuiper Belt. You may also hear the term trans-Neptunian objects used to describe those distant dwarf planets.


The Sun is larger than all of the planets put together. Everything in the Solar System orbits around the Sun. It’s mass is greater than all of the other planets combined. Even though the Sun is huge, it is small when compared to other stars in the galaxy. Even though it is smaller, the Sun provides all of the light for the Solar System. As far as astronomers are concerned, our Sun is named Sol. The entire group of Sun and planets is called the Solar System.


Everything on Earth is affected by the Sun. The Earth’s orientation to the Sun creates the seasons of the year. When your hemisphere of Earth is directed away from the Sun, it is winter. When your hemisphere is pointed closer to the Sun, it is summer. So when you’re in the Northern Hemisphere and it’s summer, kids in Australia might be skiing. As you learn more about the other planets in the Solar System, you will discover that the same idea works for most of them.

The Sun’s energy is spread around the planet, but is focused on or near the equator. That centerline of the planet is where you will find long sunny days, very little seasonal change, and the warmest ocean waters. From the equatorial regions, energy moves north and south as it circulates around the planet. That circulation can happen in the atmosphere or the oceans.


NASAs Messenger mission will soon send back new images of Mercury. If you remember anything about Mercury, remember that it is the closest planet to the Sun and really hot. Temperatures on Mercury get up to 460 degrees Celsius. An average temperature on Earth is about 15 degrees Celsius (although it has a wide range). The Sun beats down on little Mercury all day long.

The amazing thing is that there is a side of Mercury that faces away from the Sun. Temperatures on the dark side of the planet can drop to less than negative 180 degrees Celsius. It’s a whopping 640 degree temperature change from the hottest to the coldest part of the planet. The temperature ranges are a direct result of the very long days on Mercury. It takes 58 Earth days for Mercury to complete one of its days. This slow rotation affects the temperatures on the surface. Very long days allow the temperature to build for long periods of time.

As if the extreme temperatures weren’t enough, Mercury has almost no atmosphere. The loss of atmosphere also allows for extreme temperature changes. Mercury, like the Moon, is covered with craters. Because the planet has no atmosphere, the asteroids never burn off. Imagine if you put our Moon next to the Sun. That comparison helps you understand what Mercury is really like. Tons of space dust and tiny asteroids are always hitting the Earth but our atmosphere helps to burn them up before they hit the planet. Asteroids have hit Mercury for millions of years. Each hit leaves its mark like the ones on our Moon.


When Mariner 10 explored Mercury in the 1970′s we received pictures and discovered that Mercury has a weak magnetic field, but similar to Earth’s because it is a global magnetic field. Scientists think the core of the planet is made of nickel and iron. This iron acts like a huge magnet, changing the way fields interact with the planet. Something else is very interesting. It seems that Mercury lost a huge amount of its mantle/lithosphere millions of years ago. It may have hit another large object while orbiting the Sun. That fact means the layer of rock that covers the core is very thin when compared to other terrestrial planets.


Mercury is very difficult to see from Earth. Why? It is right next to the Sun. Mercury is rarely in the sky in a position where we can see it because it is only visible during the day. Also, Mercury reflects less than 10% of the light that hits it. Scientists use the word albedo to describe how much light a surface will reflect. The low albedo of Mercury tells you that the surface is very dark. We have been able to see some parts of the planet, such as the Caloris Planitia Basin. The CP Basin is a very old crater caused by an asteroid impact millions of years ago. Scientists have also seen long cliffs called scarps. They may have been created when the planet was cooling.


Special cameras have allowed us to see through the thick haze of Venus. The second planet away from the Sun is called Venus. It’s ironic that Venus is named after the Roman goddess of love and beauty. Venus is one of the harshest planets in the Solar System. It’s over 460 degrees Celsius. It has clouds of sulfuric acid in an atmosphere of carbon dioxide. Lava is found across the surface after being spewed from volcanoes. While a harsh place for you, scientists think it’s an amazing planet.


Everything we just told you is about all we know of Venus. The atmosphere is so thick on Venus that we’ve never even seen the surface. The most powerful telescope on Earth or in orbit can’t see through the thick layer of clouds that surround the planet. The Magellan probe went to Venus in the early 1990′s and sent back some interesting photos of the surface, but it had to use wavelengths of light that we can’t see. The probe used ultra-violet and infrared light. This thick atmosphere also creates a greenhouse effect that helps raise the surface temperature of the planet.

Do you remember the clouds of sulfuric acid? Those sulfur compounds in the atmosphere create Venus’ yellow color. The atmospheric reflection also makes it a very bright object in our night sky. It is easier too see with a telescope than the dark planet Mercury.

By watching the atmosphere of Venus, astronomers discovered that Venus is upside down when compared to Earth. It has a South Pole on the top of the planet and the North Pole on the bottom. Why? North and South Poles are defined by the direction a planet rotates. Since Mercury rotates in the opposite direction from Earth, its North Pole is actually on the bottom.


The Venera, Pioneer, Mariner and Magellan probes have all flown by Venus. Their instruments determined that the surface is generally smooth. The combination of an active atmosphere and lava flows creates conditions that wipe away evidence of scrapes and scratches. The probes discovered some craters, but there are no mountains. This evidence allowed scientists to conclude that there is very little possibility of plate tectonics.


Earth is the third planet from the Sun The third planet from the Sun is your home. The Earth is the only known planet where life can survive. As far as we know, there is no other planet in the universe like Earth. We have a very narrow temperature range that allows water to remain a liquid. Life has developed over millions of years because of that liquid. What else makes us special? Most of our atmosphere is made of nitrogen (N), a relatively inert gas. If we had clouds of sulfuric acid or methane (like other planets), life may have never developed.


There are also huge landmasses on our planet. The rock plates that float across the surface are called tectonic plates. Those plates float on the liquid region called the mantle. The mantle is an area between the core and the crust that is filled with molten rock. It is kept in a liquid state because of the energy given off by the center (core) of the Earth. Scientists have also discovered that pressure increases as you move towards the center of the planet. The core of the Earth has extreme temperatures and pressures that keep the iron (Fe) and other metals liquid and flowing.

Image of Aurora Australis created over the southern hemisphere


Flowing metal in our planet helps create something called a dynamo effect. Dynamos create large magnetic fields. In the case of the Earth, the magnetic field protects our planet from space. This protective cover is called the magnetosphere. It shields us from the solar winds and solar radiation. You can see where solar winds and the magnetosphere collide when you see the Aurora Borealis (northern hemisphere) and the Aurora Australis (southern hemisphere).


Although many planets in the Solar System have atmospheres, ours protects us from space and encourages life. With an atmosphere made up of 78% nitrogen (N), 21% oxygen (O), and 0.03% carbon dioxide (CO2), life has thrived on this planet. Our atmosphere has many layers divided by different temperatures and pressures. The atmosphere also provides the planet with protection. The ozone (O3) that surrounds Earth filters out ultra-violet light. The density (thickness) of the atmosphere helps to vaporize many solid particles colliding with the planet. As you can tell, the atmosphere serves many purposes.


NASA has several Mars missions planned for the next decade. Mars is the fourth planet from the Sun. It is a very active planet like the Earth. It has evidence of volcanoes, plate tectonics, and liquid water (as opposed to ice) on the planet. It even has polar ice caps like the Earth, with water in the north and solid carbon dioxide in the south. With all of these similarities, Mars is still nothing like Earth. It only has 40% of our gravity because the mass of the planet is so much smaller. Also, its atmosphere is made up of carbon dioxide and has less than 1% of the atmospheric pressure of Earth.


Scientists still hold out hope for life on Mars. Mars had lots of water. Right now, there are ice caps on the surface. At one time, there may have been water in liquid form under the surface of the planet. Recent discoveries by the Mars Exploration Rovers have proven the existence of water by discovering hematite. Where there is water, there could be life. Mars also has weather and a heat source. The atmosphere circulates around the planet and there are volcanoes on the surface.


Many probes have visited Mars through the years because it is so close to Earth. Viking, Pathfinder, Sojourner, and Mariner are only a few. The Viking Lander checked out the surface of Mars in the 1970′s. It sent back some great pictures of the red surface of the planet. The surface is a reddish color because the rocks and crust are chock full of iron compounds. For several years, the two Mars Exploration Rovers have been studying the surface rocks in detail. They have been able to travel to many locations in a small area. With patience, the rovers have made many new discoveries about the geologic history of Mars.

All of these probes have also shown us a great deal of the Martian surface. Mars has the largest volcano ever discovered. It has been named Olympus Mons and is one of the most amazing features of the planet. The Mars Reconnaissance Orbiter will soon photograph the location in higher resolution than before. The probes have also discovered many channels that cross the surface. Those channels may have been created by flowing water and erosion on the surface and the mountains.


Jupiter's Moon Io is tiny when compared to the planet. Jupiter is the largest planet in our Solar System. Its mass is over 300 times the mass of the Earth. If you look at its atmosphere and over 20 moons, you could say that Jupiter is almost like another Sun. There is only one thing missing — Heat. There is a magical time in a star’s life when nuclear reactions start and the star begins to burn. Jupiter never got to that point.

Jupiter is classified as a Jovian planet. The Jovian planets are gas giants that orbit the Sun. Gas giants don’t have solid surfaces of rock like other planets. You will find some rock at the core of the planet, but it is very little when compared to the planet as a whole. As you move deeper into the planet, you find very dense gases that have become liquids. All of the Jovian planets are huge compared to the Earth but tiny when compared to the Sun. Jupiter has a diameter of 85,000 miles while Earth is only 7,600 (the Sun is about 870,000 miles). Jupiter is often one of the brightest objects in the sky because of its size.


As you know, the bigger mass you have, the greater effect you have on the surrounding area. Well, Jupiter is huge. There is so much gravity and such a strong magnetic field that scientists discovered hydrogen gas in the outer atmosphere. No big deal. As you go deeper into the atmosphere the pressure and magnetic fields increase. Eventually you get to a layer where you find molecular hydrogen and finally liquid hydrogen right near the core of the planet. It takes an enormous amount of pressure to compress hydrogen into a liquid form.

Just because a planet is big doesn’t mean it can’t have weather and storms like Earth. On Jupiter, the storms are as big as the Earth. When the Voyager probe flew by Jupiter in the 1970s, it took some great pictures of the huge storms that last for hundreds of years. Astronomers can see the swirling and the colored bands because of the different colored compounds in Jupiter’s atmosphere. You’ll find a lot of hydrogen, methane, and ammonia gas.


Saturn isn't the only planet with rings in the solar system. Saturn is the other big planet in our Solar System. You will find its orbit just outside of Jupiter in the sixth position. It is a gaseous planet like Jupiter and those gases give Saturn a very low density. The big astronomy joke is that if you could find a lake big enough and put Saturn in the water, it would float. Its density makes it lighter than water. While knowing Saturn’s density is a fun fact, we know that the thing you will remember is that Saturn is the planet with the big rings. While other planets in our Solar System have rings, Saturn’s can be seen from Earth. The Cassini spacecraft is studying the moons and rings of Saturn for several years.


Saturn is the second largest planet in the Solar System. It’s huge compared to Earth. When you think of a day on Earth, it is 24 hours. A day on Saturn is only about 10.7 hours. It is amazing that a planet that has a diameter almost 10 times that of the Earth spins more than two times as fast. The speeds at the equator are staggering. That speed also gives Saturn a bulge at its equator. It is not like a sphere at all.

Scientists have also discovered that Saturn is like Jupiter in that it has metallic hydrogen swirling through its atmosphere. Its atmosphere is almost 99% hydrogen. There are also helium and ammonia in small amounts. The ammonia gives Saturn its tan color. Again, like other Jovian planets, Saturn does not have a surface like other planets. Its rocky core is small compared to the ice and hydrogen layers.


Only a few probes have made it to Saturn. Pioneer and Voyager I and II all did flybys of the planet and rings. They confirmed a special fact about Saturn and some other Jovian planets. Saturn is self-luminous. Self-luminous means that it gives off more light than it receives. The Sun gives off a certain amount of light and some of it makes it to Saturn. Saturn’s composition actually makes it glow, so its brightness is greater than the amount of light it reflects.

Currently, the Cassini-Huygens probe is studying Saturn. About six months after the probe’s arrival, the Huygens lander was released to study the atmosphere and surface of Saturn’s moon Titan. Titan is the only moon in our Solar System that has a measurable atmosphere. As the lander descended, it sampled the atmosphere and discovered rivers of liquid methane on the surface of the planet.


We don't have many good pictures of the gas giant Uranus. The seventh planet from the Sun is Uranus. William Hershel discovered it in 1781. It is one of the four gas giants in our Solar System, but is much smaller than both Jupiter and Saturn. You will find that Uranus is similar in some ways to Neptune, the eighth planet. Only one Voyager probe has flown by Uranus so very little is known about the planet.

Like other planets we discussed, Uranus is a planet largely composed of gases. It has a light blue color because of the methane in its atmosphere. The atmosphere of hydrogen, helium, and methane is constantly swirling around the planet. As you move from the core to the surface of the atmosphere, you will discover liquid rock, ice, and molecular hydrogen. There is no layer of metallic hydrogen like Jupiter and Saturn.


Scientists also discovered something very special about Uranus’ axis. Instead of orbiting on an axis like the other planets (up and down), Uranus spins almost on its side. When you see pictures of the Earth rotating, you see it spinning a little off-center. Uranus spins on a horizontal axis, not a vertical one.


Astronomers have also determined that Uranus is smooth. There is so much going on in the atmosphere and so little activity in the core that the surface doesn’t change. If an asteroid hits the planet, the swirling storms wipe the craters away. Although the storms swirl around the planet, there are few distinct clouds. The atmosphere moves as a constantly mixing soup.


Neptune is the most distant gas giant from the Sun. Neptune is the eighth planet form the Sun. It wasn’t discovered until 1846. It wasn’t even actually seen with a telescope for several years after that. Astronomers noticed some funny movements in the orbit of Uranus. The changes in the expected orbit were so large than they decided another planet must exist. They made the calculations, looked in the right place, and found Neptune.


Neptune is huge in size compared to Earth. When you compare it to the other gaseous planets like Jupiter and Saturn, it is the smallest. Like the other Jovian giants, Neptune’s atmosphere is made up of hydrogen and helium. It also has large amounts of methane that give it a deep blue tint. It is very similar to Uranus.

See that big swirl in the atmosphere? Just like Jupiter, Neptune has large storms swirling in its atmosphere. When Voyager II passed by, it took pictures of a storm that was big enough to hold the Earth. The storm was moving at more than 500 miles per hour. The speeds inside of the storm could have been more than seven times the speed of the fastest winds on Earth.


Voyager II was the only probe that ever made it to Neptune. It was able to fly by on its way out of the Solar System. It discovered new moons around the planet, bringing the total to eight moons. Its photos also confirmed that Neptune has very thin rings around the planet.


Even with advanced telescopes, Pluto is still difficult to see. We didn’t even know that Pluto existed until the 1930′s. Astronomers studied the orbit of other planets in the area and noticed a little wobble. The wobble was big enough for astronomers to start looking for a source. Eventually Clyde Tombaugh found Pluto. In recent years, additional large bodies have been discovered just beyond Pluto’s orbit.

For such a small object, there is a lot of debate about Pluto. Its size is one of the big reasons that astronomers stated that it is no longer considered a true planet. The International Astronomical Union (IAU) met in August 2006 and decided that Pluto would be classified as a dwarf planet. The change comes because of Pluto’s size and eccentric (strange) orbit. It passes in an out of the orbit of Neptune and doesn’t orbit in the same plane as the other planets. It’s a weird little object. Astronomers decided that this weird little object would no longer be a planet. Even though a small object, Pluto has its own satellite (moon) named Charon.


If you say the distance from the Earth to the Sun is 1. Then the average distance from Pluto to the sun is 39.5. That is a really long way. When you are an object that far away from the Sun, you are missing some things. First, there will be very little light. Second, you will get very little energy from the Sun and your planet is going to be mighty cold. Scientists speculate that the average temperature on Pluto is 37 Kelvin. Ice freezes at 273 Kelvin. Brrrr.

Pluto’s orbit is also special. It crosses Neptune’s orbit and is closer to the Sun for several years at a time. This more elliptical orbit has scientists wondering if it is really the largest object in the Kuiper Belt. The Kuiper Belt is the home of thousands of small objects that orbit the Sun beyond Pluto. The recent decisions by the IAU will term many round bodies to be called dwarf planets.


So is it a Jovian or terrestrial? Gas or rocky? Right now, it’s neither. If you had to force it, lean towards terrestrial. The Pluto’s diameter is only about 60% the diameter of the moon. It is so small that it is able to rotate once every six days. Even though small and incredibly cold, astronomers believe it has a very thin atmosphere of nitrogen. In January of 2006, the New Horizons mission launched to study Pluto and objects in the Kuiper Belt. The spacecraft should reach Pluto by 2015 and the Kuiper belt in 2016.


There are many more objects in our solar system than the planets. If you finished the main Solar System section, you now understand that our system has one star and nine accepted planets. Given that basic information, we want to let you know that there is much more in our little system than those ten objects.


Sure, you can see a planet. They are tough to miss. As you continue exploring, you will find moons around almost every planet. While the Earth only has one, other planets have more than twenty moons. You also know that you can see rings made of small pieces of dust and ice that circle Saturn and other gas giants.

As you look for smaller objects in the system, you will find a field of asteroids in orbit around the Sun between Mars and Jupiter. There are also stray asteroids flying through the Solar System. Comets are also found orbiting the Sun. The amazing thing is that there may still be other objects in our Solar System. That’s one of the exciting things about astronomy… There are still millions of things to discover in the universe.


There are also many things we can’t see in the Solar System. There are small particles and energies swirling throughout the system. Many of these unseen energies are created by the Sun. We have a heliosphere that surrounds our entire system and Voyager has just reached the heliopause (the edge). The Sun also gives off small particles called the solar wind, light, and various types of radiation. While Earth needs to be protected from some of these forces, the energy that creates the heliosphere is protecting every object in our system.


Its a cold and empty universe for a single asteroid orbiting the Sun. Asteroids are different from comets. They are like small pieces of planets. Some asteroids that orbit planets are even considered moons. One of the moons of Mars (Deimos) is only four miles across. In our Solar System, you will find asteroids orbiting the Sun in a regular orbit (not like comets, which have stretched elliptical orbits). There is also an Asteroid Belt between the orbits of Mars and Jupiter. The belt holds small pieces of rock that spin around the Sun in a specific orbit. It is almost like a planet that never formed.


Asteroids are made of rocks and metals. Some astronomers consider them to be minor planets (like the moons of Mars and Saturn). Most asteroids are very small but they do have gravity and can affect any objects that come too close. The more iron (Fe) and nickel (Ni) in the makeup of an asteroid, the greater its mass (and gravity). Scientists also use the amount of metal in asteroid classification. Using an infrared sensor, asteroids are classified as light or dark. The lighter ones have more metal than the darker ones.


Beyond our Solar System, asteroids travel through the galaxy from system to system. These asteroids do not necessarily orbit a star but stars influence their direction and speed. Many astronomers believe that asteroids are pieces from the origins of the universe. Some asteroids were large enough and lucky enough to combine with others and form planets. Some asteroids just continued their existence floating through the universe.


Chances are the Earth doesn’t have to worry about a collision with a comet. Asteroids are another matter. Scientists already think that a large asteroid may have hit the Earth when the dinosaurs were alive. That collision may have changed our atmosphere and led to the extinction of the dinosaurs.

We just told you about that asteroid belt just outside Mars’ orbit. There may come a day when one of those asteroids drops out of orbit (maybe from a collision with another asteroid) and heads toward Earth. If it is small enough, it will burn up in the atmosphere. Larger ones will hit the surface of the planet. Hundreds of millions of years ago, collisions with asteroids happened more often. Over time, the number of asteroids in the path of the Earth decreased and collisions became less frequent.


The surfaces of comets become more active as they approach the Sun. Comets are small chunks of ice and dirt that fly through systems in long, wild orbits. They are created when a planetary system develops. Nearly all comets orbit a star while asteroids may move through the galaxy as remnants from the creation of the universe. Comets are closely related to the formation of systems. They are left over pieces of frozen gases and water that were never absorbed by the forming planets.


You may know that planets move in elliptical orbits around their sun. An ellipse is a shape that is like a narrow circle. Comets move in very narrow and stretched out ellipses. They sometimes cross the orbits of several planets on their trip around their sun. Comets also have tails. Those tails are streams of gas and dust that follow the comets for thousands of miles. Comets aren’t really on fire. The light you see is reflected light from the closest star. The light is reflected off the gases, ice, dirt, and dust that travel with the comet.


Every comet is special and unique. They each have distinct orbits around a star and a unique chemical makeup. Even though they are all different, scientists categorize them by how long it takes them to complete an orbit around the Sun. There are long-period comets and short-period comets. Long-period comets usually take over 200 years to orbit the Sun. Short-period comets make it around in less than 200. Halley’s Comet is famous and orbits the Sun once every 76 years. Comet Kohoutek has a period of 75,000 years.


In the same way that we send probes to look at other planets, we also spacecraft to study comets. In 2004, the Stardust mission encountered Comet Wild2 and collected samples. Astronomers hope to learn more about the origins of the Solar System and the universe from those particles. The most interesting compounds will be those that contain carbon because they may hold the keys to the origins of life. Comets could have hit the Earth millions of years ago and helped seed organic (carbon-based) life. The Deep Impact mission sent a projectile to collide with a comet. The spacecraft then analyzed the scattered dust and ice.


Our asteroid belt can be found between the orbits of Mars and Jupiter. The Solar System has eight planets, smaller dwarf planets (like Pluto), and a star. Between the fourth (Mars) and fifth (Jupiter) planets is a special place. Astronomers call this region the asteroid belt because there are millions of tiny asteroids in this region. These objects circle the Sun just like a planet might. Sometimes they fall out of orbit and head towards the Sun, crossing the orbital path of the Earth.

As we said, the asteroid belt is made of millions of pieces of rock and dust. There could be over 40,000 larger ones. The largest discovered asteroid is about 900 miles across. As time passes, the size of the asteroids will decrease. As they orbit the Sun, they constantly hit each other and break into smaller pieces. Those collisions are sometimes the cause of asteroids being knocked out of orbit.


Astronomers think that the asteroids are leftover pieces of the Solar System. As other large objects in the system combined to form planets, there were some smaller pieces left over. Their location between Mars and Jupiter could also influence the pieces. They may have never formed a small planet because of the gravitational pulls of Jupiter (very strong) and Mars (very weak). The pulling of the two planets keeps the asteroids separated and circling the Sun in a doughnut shaped area.


Astronomers think there may be other very small asteroid belts in our system. Many small pieces of rock are in orbit between Earth and Mars. There are also pieces in orbit between Mercury and the Sun. The smaller fields are not as large as the one outside of Mars, but they do seem to hold a larger number of asteroids than the very empty areas of the Solar System. There are even hints that other systems have similar fields of asteroids.


There may be many small dwarf planets beyond pluto in the Kuiper belt. Is there anything beyond Pluto? Yes. Thousands of small objects orbit the Sun beyond Pluto. Most are found in an area called the Kuiper Belt. You will find asteroids, comets, dwarf planets, and other small solar system bodies. The objects you find out there are also called Trans-Neptunians (beyond Neptune). Astronomers have only begun to examine the area since 1992. It takes special probes and telescopes to study the area.

The Kuiper Belt is like the asteroid belt in some ways. A very large area looks like a flattened doughnut. The shape is also called a toroid. Astronomers believe the area holds pieces that have remained the same since the beginning of the Solar System. You start to encounter objects in the Kuiper Belt at about 50 times the distance from the Earth to the Sun. The edge of the Solar System is about 100 times the distance from the Earth to the Sun.


As we said, there are many asteroids found in the Kuiper Belt. Many of them have diameters more than 50 miles across. Astronomers also believe that many short-period comets begin their lives in the belt. An example of a short-period comet is Halley’s Comet with a period of 76 years. Short-period comets make a complete elliptical orbit in less than 200 years. Comets that take longer to complete a trip around the Sun are called long-period and are usually found in the Oort Cloud.


As time passes, astronomers will learn more about the objects in the Kuiper Belt. They currently have records of over 70,000 objects (mainly asteroids). Because they are so far away, they are very difficult to study. Imagine trying to look at a black rock (in black space) that is only 50 miles across from about 46.5 billion miles away. That’s what scientists have to deal with.

In January 2006, the New Horizons mission was launched to study Pluto and objects in the Kuiper Belt. The spacecraft should reach Pluto in 2015 and then continue through the belt in 2016. There are many discoveries to be made in the farthest reaches of our Solar System.

-Now, enjoy these fantastic activities and videos about the universe and the solar system! (Build your own solar system) (An interactive solar system) (Click a planet to choose your destination) Journey to the Edge of the Universe


Energy Comes in Many Forms

Can you imagine a world without energy? You wouldn’t be able to play computer games, ride a bicycle, or talk on the phone. Cars and trucks wouldn’t move. Lights wouldn’t shine. Plants wouldn’t grow. Without energy, nothing would happen!

Energy is the ability to change or move matter.

Just about everything you see, hear, and feel depends on energy. Energy comes in many forms.

Chemical energy is energy that is released by a chemical reaction. The food you eat contains chemical energy that is released when you digest your meal. Wood, coal, gasoline, and natural gas are fuels that contain chemical energy. When these fuels are burned, the chemical energy is released as heat.

Radiant energy is energy that can move through empty space. The sun and stars are very powerful sources of radiant energy. The heat and light given off by lightbulbs and campfires are also forms of radiant energy.

Mechanical energy moves objects from place to place. You use mechanical energy when you kick a ball or turn the pedals of a bicycle. Other examples of mechanical energy include water flowing in a stream or tires rolling down a road.

Electrical energy comes from the electrons within atoms. It can be created at a power plant or inside a battery, and can power everything from remote-controlled cars to refrigerators. Lightning and static electricity are also forms of electrical energy.

Nuclear energy is energy contained in the nucleus at the center of an atom. Nuclear energy is released when nuclei are split apart into several pieces, or when they are combined to form a single, larger nucleus.

Meet the Atom

An atom is the smallest unit of matter. Scientists so far have found 112 different kinds of atoms. Everything in the world is made of different combinations of these atoms. Every atom has a nucleus in the center. Tiny particles called electrons travel around the nucleus. The flow of electrons produces electricity.

Energy Can Move and Change

Energy can be transferred, or moved, from one object to another.

When you ride a bicycle, you transfer mechanical energy from your legs to the pedals. The pedals transfer the energy to the bicycle gears, which transfer the energy to the tires. The rolling tires move the bike along the street.

When a cat sits on a sunny windowsill, radiant energy from the sun is transferred through the window to the cat’s fur. The radiant energy heats up the fur and the cat’s body.

Energy can be transformed, or changed, from one form to another.

Suppose you eat a hamburger for lunch. Later that afternoon, you run in a race. Your body, through the digestive process, changes the chemical energy in the hamburger to the mechanical energy of your arms and legs so you can run.

A toaster changes electrical energy to heat. Electricity flows into the toaster’s heating elements, which are made of wires. The flow of electricity heats the wires. Heat from the wire is transferred to the slice of bread. Up pops your toast!

A car changes the chemical energy of gasoline to the mechanical energy of wheels turning. Inside a car’s engine, gasoline is burned in small bursts. Each burst of energy creates motion in the engine’s crankshaft and other moving parts. This motion is transferred to the wheels of the car, making them turn.

Many Different Energy Resources Can Be Used to Make Electricity

You probably know that most of the electricity you use is produced in a power plant and travels to your home and school through special wires. But do you know what energy sources are used to run power plants?

Energy resources can be divided into two categories: nonrenewable and renewable.

Nonrenewable Resources

A nonrenewable resource is a resource that can be used up. Fossil fuels, which include coal, oil, and natural gas, are nonrenewable because it took millions of years for them to form. Once we use up our fossil fuels, they will be gone for good.

Many power plants use fossil fuels. The fossil fuel is burned to produce heat, which is used to make steam. The steam is then used to turn the blades of a turbine.

Some power plants run on nuclear power, which is another nonrenewable resource.

Nuclear power plants rely on uranium, a type of metal that is mined from the ground and specially processed. Heat released from splitting uranium atoms is used to convert water into steam that turns turbines.

Renewable Resources

A renewable resource is fairly easy to replace. Renewable energy resources include wood, wind, sunshine, geothermal energy, biomass, and water stored behind dams in lakes and reservoirs. Electricity can be produced using several kinds of renewable resources.

Wind energy can produce electricity in regions where steady winds blow. Giant wind turbines capture the wind’s energy and use it to power generators.

Biomass is material that is formed from living organisms, such as wood or agricultural wastes. Biomass can be burned to produce electricity, or be converted to a gas and used for fuel. 

Geothermal energy uses hot water or steam from deep beneath the earth’s surface to produce electricity.

Hydroelectric power plants use the energy of falling water to spin generator turbines.

Solar energy can also be used to produce electricity. Solar cells change the radiant energy of the sun into electrical energy. Some calculators and portable radios are powered by solar cells. Solar panels, or modules, placed on a rooftop can supply electricity to the building below.

Energy Resources Today

The energy resources people use today can be divided into two categories: nonrenewable and renewable.

Nonrenewable Resources

Nonrenewable resources cannot be replenished. We have limited supplies of them, and when these supplies are gone we will not have any more.

Fossil fuels were formed from the fossilized remains of tiny plants and animals that lived long ago. Most electricity used in the world is generated from power plants that burn fossil fuels to heat water and make steam. The highly pressurized steam is directed at turbine blades to make them spin.

The three forms of fossil fuels are coal, oil, and natural gas.

  • Coal is a hard, black, rock-like substance made up of carbon, hydrogen, oxygen, nitrogen, and sulphur. There are three main types of coal: anthracite, bituminous, and lignite. The precursor to coal, called “peat,” is still found in many countries and is also used as an energy source. Coal is found in many parts of the U.S. and throughout the rest of the world.
  • Oil is a liquid fossil fuel, sometimes also called petroleum. It is found underground within porous rocks. To obtain oil, companies drill down to deposits deep below the earth’s surface using oil rigs. More than half of all the oil we use in the U.S. comes from outside our country—most of it from the Middle East.
  • Natural gas is made up primarily of a gas called methane. Methane gas is highly flammable and burns very cleanly. Natural gas is usually found underground along with oil. It is pumped up and travels through pipelines to homes and businesses. Natural gas supplies are abundant from sources in the U.S. and Canada.

Nuclear power uses heat released from splitting atoms to convert water into steam that turns turbines. Nuclear power plants rely on uranium, a metal that is mined and specially processed. Fuel rods containing uranium are placed next to each other in a machine called a nuclear reactor. The reactor causes the uranium atoms to split and in so doing, they release a tremendous amount of heat.

Renewable Resources

Renewable energy resources can be replenished in a short period of time, so they will never be all used up. Energy companies around the country are using renewable resources more and more to generate electricity.

Biomass is organic matter, such as agricultural wastes, wood chips, and bark left over when lumber is produced. Biomass can be burned in an incinerator to heat water to make steam, which turns a turbine to make electricity. It can also be converted into a liquid or gas, which can be burned to do the same thing.

Biomass includes energy crops like wood, straw, and other crops grown primarily for use as a fuel. Energy crops are renewable, but some, like trees, take a long time to grow.

Farmers can grow trees on some of their land instead of wheat or other kinds of food. The wood is harvested regularly, cut into small chips and burned to provide heat or run small electric power plants.

Another type of biomass is methane gas, a by-product of decay in landfills. As garbage rots in the ground, it gives off gases that can be collected and burned to produce heat or electricity.

Geothermal energy is steam (or hot water that has been converted to steam) from deep inside the earth. Our planet’s interior is very hot—at its core, 4,000 miles deep, temperatures may reach over 9,000°F. This heat is continuously conducted from the earth’s core to the surrounding layer of rock, the mantle.

There are some places around the earth where magma (hot molten earth from the mantle) pushes up through cracks into the crust near the earth’s surface. Magma can heat nearby rock and water as hot as 700° F. Some of this hot water reaches the earth’s surface as hot springs or geysers, and some stays trapped deep underground in cracks and porous rocks. This hot water can be used directly or converted into steam to turn turbines that generate electricity. (The word “geothermal” comes from the Greek words geo, for earth, and therme, for heat. So geothermal means “earth heat.”)

 Hydrogen is a colorless, odorless gas. Hydrogen can be converted into electricity through a chemical reaction in a device called a fuel cell. Converting hydrogen into electricity produces no pollution—only water and heat.

If the hydrogen comes from a renewable resource like landfill gas, fuel cells are considered renewable. However, if it comes from a nonrenewable resource like fossil fuels, fuel cells are considered nonrenewable.

Today, NASA uses hydrogen fuel cells to convert hydrogen into electricity for astronauts. There are already some cars that run on hydrogen. In the future, hydrogen will be used to fuel vehicles and airplanes and to provide electricity to buildings.

Hydropower uses the power of falling water to generate electricity. Water that is stored behind a dam is released and directed through tubes to flow against turbine blades and make them turn. Most hydropower facilities are found in hilly or mountainous areas. Hoover Dam is the most famous hydroelectric facility in The USA.Ocean energy is a form of hydropower. Oceans cover more than 70% of the earth’s surface, making them the world’s largest solar collectors. The ocean stores thermal (heat) energy, which can be used to generate electricity using special turbine generators.

The energy of the ocean’s waves and tides can also be used to generate electricity with dams that force ocean water through turbines. This is called tidal energy, or wave power. The world’s first wave power station is on the Scottish island of Islay. It generates enough electricity for about 400 homes. Scientists and engineers around the world are working on systems to use the ocean’s energy on a large scale.

Every day, more solar energy falls to the earth than all the people on earth could use in 27 years! Special panels of solar cells, or modules, can capture sunlight and convert it directly into electricity. These panels are known as photovoltaic, or PV. (“Photo” is Greek for light, and “voltaic” pertains to electricity.) The electricity they produce can be used right away, fed into the power grid for others to use, or stored in a battery so it is also available on cloudy days.

Another form of solar energy is used for solar hot water collectors, which allow water to be heated by the sun.

Wind power is renewable energy that uses the force of the wind to spin turbines. These spinning turbines generate electricity.

Most wind power is produced at wind farms, which are large groups of turbines in consistently windy locations. A very large wind farm can generate enough electricity for all the homes in a city of about one million people. Small wind turbines can be used for individual homes, businesses, and boats. They can be used to pump water, or the electricity can be stored in large batteries for use at another time.

To finish, this table will clarify the contents explained before:

Energy-Using Item Energy Source Form(s) of Energy
space heater electricity electrical; radiant
fireplace wood or natural gas chemical; radiant
kitchen stove natural gas or electricity chemical; radiant; electrical
ceiling fan electricity electrical; mechanical
portable radio battery chemical; electrical
alarm clock battery or electricity chemical; electrical
CD or DVD player electricity electrical
portable CD player battery chemical; electrical
portable calculator solar cell radiant
car gasoline chemical; mechanical
clothes washer electricity electrical; mechanical
bicycle food chemical; mechanical

-Finally, enjoy the following activities and videos about energy!


Light plays a very important role in our lives. Without light we would not be able to see. Light from the sun generates heat, and can be used to generate electricity. To do this, light must travel to us.

Seeing the Light

Let’s take a moment to talk about visible light. As you can tell by the name, visible light is the light that humans can see. More specifically, you see the light that is not absorbed by objects. Green plants are green because they absorb all of the colors of the visible spectrum except the green color (you could also say the green wavelengths). A red wall is red to your eyes because it is not absorbing light from the red wavelengths. Mirrors reflect all of the colors of visible light.

We describe the world the way we see it as humans. Other living things on Earth see the world in different ways. Dogs only see things in black, white and gray. Some insects see colors that none of us can see. When you are learning about visible light you should remember we mean visible to humans. We should also mention that not all humans can see all the colors. There is an eye defect called color-blindness that affects many men. Color-blind men cannot see certain colors of the spectrum. It has to do with a genetic defect in their eyes.

Edges of Visibility

Although we can’t see them with our eyes, some wavelengths of light that bookend the visible spectrum are also important. Infrared radiation is next to the red portion of the spectrum. Infrared light is heat. Scientists use infrared light sensing optics when they want to see differences in temperature. Ultraviolet radiation (UV) is just beyond the violet end of the visible spectrum. UV light is given off by the Sun and absorbed by ozone in the atmosphere. Ultraviolet light can also mutate cells in your skin and give you skin cancer.

Reflection Basics

When a light ray hits an object and bounces off, it is called reflection. When you think of reflection, think about mirrors. They reflect all of the light. That is the reason you can see yourself. Even the ocean reflects light, just not all of it. If you are above the ocean, you can’t see the reflection that well, but when you are at an angle, look closely; you can see a reflection of the sky. So the ocean only has partial reflectivity.

Refraction Basics

When light moves from one substance to another it changes speed and direction. That change in direction is called refraction.

Bending Light with Refraction

Lenses are pieces of glass that bend light. The easiest thing to think about is lenses in eyeglasses. People who do not have 20/20 vision might see things a little out of focus. They wear glasses or contact lenses to make their sight clearer. Those glasses have specially ground lenses that bend the rays of light just enough to focus the image for the person to see properly. All lenses bend and refract rays of light.

In the refraction section we said that light changes speeds when it moves from one medium to another. A medium is a substance like water, air, or glass. When light slows down or speeds up it changes direction a little bit. There are three basic shapes that a lens can have: concave, convex, and planar. A concave shape is bowed inward, like looking into a mixing bowl. Convex is just the opposite, bowed outward. Have you ever seen those mirrors in the grocery stores, where everything is reflected in a spherical way? That’s convex. Planar is just that, a plane. It’s a flat surface. Just think of a planar mirror on your wall.

Using Lenses

Telescopes and microscopes are excellent examples of how lenses are used every day. By using different combinations of lenses, light is focused to create an image we could not see with the naked eye. Telescopes are able to see very distant objects that are very small to our sight and magnify them so we can see the details. The larger telescopes offer a greater ability to see objects that are more distant. Microscopes work with a similar idea but are concerned with size, not distance. Microscopes enlarge very small objects that are close to the viewer.

Using Prisms

Prisms are a very special type of lens. When refraction is at work in a prism it breaks the beam of visible light into its basic colors. In visible light, the magic colors you can see are red, orange, yellow, green, blue, indigo, and violet. Scientists say ROY-G-BIV. A prism is made up of two planar surfaces at an angle. It uses the slower speed of light in glass to its advantage by refracting the light twice. Because of the different wavelengths of light, each color is refracted a different amount. When the light ray leaves the prism, it speeds up again (entering the air) and refracts a second time. That second dispersal creates the colorful spectrum of colors.

The world around you is full of wonderful colors. The beautiful flowers, the green meadows and the blue sky show different colors. We see colors only when light is shining. When it is dark we cannot see colors.

Sunlight is made up of a number of colors but what you see is really white color. When all the Sun’s colors are mixed together, the resulting color is white. Different colors of the light travel at different speeds in glass and in water. When the white light of the sun passes from air to water or air to glass, the different colors of the sunlight bend at different angles thus separating into the individual colors we see.

Scientists generally use a glass triangle called a prism to experiment with light, when the white light hits the glass prism, each color of the light bends at a different angle and the different colors separate into a rainbow.

During a summer rain, we often see a rainbow when the sun is out. Each drop of water falling down acts as a prism. As the sunlight passes through these raindrops, the light rays bend and separate into the 7 colors of the rainbow. The colors always separate in the same order as violet, indigo, blue, green, yellow, orange, and red. To see any colors, the retinal cone cells must be stimulated by light.
The color of anything depends on the type of light sent to our eyes; light is necessary if we are to have any perception of color at all. An object is “colored,” because of the light it reflects—all other colors are absorbed into that specific object. For example, a leaf appears green because it reflects the green light and absorbs the rest of the colors.

You can see color when receptor cells (called cones) on your eye’s retina are stimulated by light. There are three types of cones, each sensitive to a particular color range. If one or more of the three types of cones becomes fatigued to the point where it responds less strongly than it normally would, the color you perceive from a given object will change.

Enjoy these activities and video about light! Exercise about shadows Transparent, translucent and opaque objects Video about light, reflection and refraction


Moving Electrons and Charges

 Electricity is related to charges, and both electrons and protons carry a charge. The amount of the charge is the same for each particle, but opposite in sign. Electrons carry a negative charge while protons carry positive charge. The objects around us contain billions and billions of atoms, and each atom contains many protons and electrons. The protons are located in the center of the atom, concentrated in a small area called the nucleus. The electrons are in motion outside of the nucleus in orbitals. The protons are basically trapped inside the nucleus and can’t escape the nucleus. As a result, it is moving electrons that are primarily responsible for electricity.

There aren’t a lot of places that you can see electricity. The most commonly- observed form of electricity is probably lightning. Lightning is a big spark that occurs when lots of electrons move from one place to another very quickly. There are three basic forms of lightning, cloud to cloud, cloud to surface, and surface to cloud. All are created when there is an unequal distribution of electrons. You can also see smaller arcs of electrons at home when you scuff your feet and then touch something like a metal doorknob (static electricity).

Electricity Around You

It’s easy to see the uses of electricity around you. In fact, there are charges around your computer, your house, and your city. Electricity is constantly flowing through all of the wires in your town. There is also electricity in your flash light. That kind of electricity created by batteries is called direct current. The other major type is found in the outlets of your house. That household form of electricity is called alternating current.

Battery Basics

The best real-life example of direct current is a battery. Batteries have positive (+) and negative (-) terminals. If you take a wire and connect the positive and negative terminals on a battery, the electrons in the wires will begin to flow to produce a current. You can prove that the current is flowing if you connect a small light to the circuit. The light will begin to glow as the electrons pass through the filaments.

DC power is used all over the world. You will probably use direct current power whenever you carry something around that uses electricity. Everything that uses batteries runs on DC power. Other countries use more portable power supplies because they might not have electric wiring in their houses.

That electric wiring in your house is AC power and it is completely different than DC. There are machines that can convert DC to AC power. Those machines might be used to take a DC battery in a boat and convert the power to AC so that a refrigerator can use it.

Cheaper and Stronger

 Why do we use AC power all over the world? It’s cheaper and easier to make devices for AC power. It is less expensive because you can increase and decrease the current for AC power very easily. The power switches for AC power are also less expensive to manufacture. Probably the biggest advantage of AC is that you can use high voltages with small currents to reduce losses when you transmit power. Remember that lost energy increases the more collisions you have, and reducing current decreases the amount of collisions (and reduces heating in the wires). You can send power with DC, but the DC power transmission loses a lot of energy. You would have to put much more effort into sending DC power over the same distance.

Alternating Around You

BIG NOTE: NEVER touch the outlets in your house. You will get electrocuted. There is more to electricity than voltage. It’s the current that will kill you.

The easiest place to see AC power in action is in your house. All of the appliances and lights in your house probably run off of AC power. There are also power converters that change DC power into AC power when you need electricity and there are no plugs around (like camping).

Conductors and Conductivity

 There are many materials that allow charges to move easily. They are called conductors. Conductors have the quality of conductivity. I guess that’s not a lot of help for you. The reality is that you just need to understand the difference between those two words. The conductor is the object that allows charge to flow. Conductivity is a quality related to the conductor. A material that is a good conductor gives very little resistance to the flow of charge. This flow of charge is called an electric current. A good conductor has high conductivity.  Metals are traditional conducting materials. You see them around the house all of the time. It’s a metal wire or one of the metal prongs in an electric plug. There are a lot of free electrons in metallic conductors. Free electrons are electrons that are not being held in atoms, and so, can move easily. Some of the best metallic conductors are copper (Cu), silver (Ag), and gold (Au).

Force of Charges

Scientists discovered that opposite charges attract, and like charges repel. So positive-positive and negative-negative would repel, while positive-negative would attract. Physicists use the term electric force to describe these attractions and repulsions. The electric forces are much stronger when negative charges are closer to positive charges. The further apart two charges are, the weaker the electric force. Also, the greater the charges, the greater the electric force will be.

Electric Fields

An electric field describes the funky area near any electrically-charged object. Scientists don’t use the word “funky”, but it works. It could also be called an electrostatic field. There are two kinds of charges, and some combinations attract while others repel. So, if the central charge was positive, and you put another positive charge near it, that second charge would be repelled outward. If the central charge is negative, a positive charge placed nearby would be attracted toward the center charge. Electric fields can also be created by magnetic fields. Magnetism and electricity are always connected.

What is a Magnet?

 A magnet is an object or a device that gives off an external magnetic field. Basically, it applies a force over a distance on other magnets, electrical currents, beams of charge, circuits, or magnetic materials. Magnetism can even be caused by electrical currents.

While you might think of metal magnets such as the ones you use in class, there are many different types of magnetic materials. Iron (Fe) is an easy material to use. Other elements such as neodymium (Nd) and samarium (Sm) are also used in magnets. Neodymium magnets are some of the strongest on Earth.  Most of the magnets you see around you are man-made. Since they weren’t originally magnetic, they lose their magnetic characteristics over time. Dropping them, for example, weakens their magnetism; as does heating them, or hammering on them, etc.

Electromagnets have a ferromagnetic material (usually iron or steel) located inside of the coils of wire.
They depend on currents of electricity to give them magnetic characteristics. Not only can they be turned on and off, but they can also be made much stronger than ordinary magnets.  Series and Parallel Circuits (Video)  Game about building a circuit How to build a simple buzzer  Electricity and magnetism


Mechanics and Motion

Motion is one of the key topics in physics. Everything in the universe moves. It might only be a small amount of movement and very very slow, but movement does happen. Don’t forget that even if you appear to be standing still, the Earth is moving around the Sun, and the Sun is moving around our galaxy. The movement never stops. Motion is one part of what physicists call mechanics. Over the years, scientists have discovered several rules or laws that explain motion and the causes of changes in motion. There are also special laws when you reach the speed of light or when physicists look at very small things like atoms.

Speed it Up, Slow it Down

The physics of motion is all about forces. Forces need to act upon an object to get it moving, or to change its motion. Changes in motion won’t just happen on their own. So how is all of this motion measured? Physicists use some basic terms when they look at motion. How fast an object moves, its speed or Velocity, can be influenced by forces. (Note: Even though the terms ‘speed’ and ‘velocity’ are often used at the same time, they actually have different meanings.) 

Acceleration is a twist on the idea of velocity. Acceleration is a measure of how much the velocity of an object changes in a certain time (usually in one second). Velocities could either increase or decrease over time. Mass is another big idea in motion. Mass is the amount of something there is, and is measured in grams (or kilograms). A car has a greater mass than a baseball.

Simple and Complex Movement

There are two main ideas when you study mechanics. The first idea is that there are simple movements, such as if you’re moving in a straight line, or if two objects are moving towards each other in a straight line. The simplest movement would be objects moving at constant velocity. Slightly more complicated studies would look at objects that speed up or slow down, where forces have to be acting.

There are also more complex movements when an object’s direction is changing. These would involve curved movements such as circular motion, or the motion of a ball being thrown through the air. For such complex motions to occur, forces must also be acting, but at angles to the movement.

In order to really understand motion, you have to think about forces, acceleration, energy, work, and mass. These are all a part of mechanics.

Forces of Nature

 Forces are a big part of physics. Physicists devote a lot of time to the study of forces that are found everywhere in the universe. The forces could be big, such as the pull of a star on a planet. The forces could also be very small, such as the pull of a nucleus on an electron. Forces are acting everywhere in the universe at all times.

Examples of Force

If you were a ball sitting on a field and someone kicked you, a force would have acted on you. As a result, you would go bouncing down the field. There are often many forces at work. Physicists might not study them all at the same time, but even if you were standing in one place, you would have many forces acting on you. Those forces would include gravity, the force of air particles hitting your body from all directions (as well as from wind), and the force being exerted by the ground (called the normal force). 

 Let’s look at the forces acting on that soccer ball before you kicked it. As it sat there, the force of gravity was keeping it on the ground, while the ground pushed upward, supporting the ball. On a molecular level, the surface of the ball was holding itself together as the gas inside of the ball tried to escape. There may have also been small forces trying to push it as the wind blew. Those forces were too small to get it rolling, but they were there. And you never know what was under the ball. Maybe an insect was stuck under the ball trying to push it up. That’s another force to consider.

If there is more than one force acting on an object, the forces can be added up if they act in the same direction, or subtracted if they act in opposition. Scientists measure forces in units called Newtons. When you start doing physics problems in class, you may read that the force applied to the soccer ball (from the kick) could be equal to 12 Newtons. 

Velocity, Speed, and Motion… Oh My!

Velocity and speed are very similar ideas, but velocity is a vector, and speed is not. Suppose we knew that someone was driving at thirty-five kilometers an hour (35 km/hr), but the direction wasn’t given. How would you draw an arrow to represent a vector? You can’t know how to draw the vector if you only have one value (either amount or direction). In this example, you were never told about the direction. Physicists would say that the speed is thirty-five kilometers an hour (35 km/hr), but the velocity is unknown. On the other hand, if you’re moving at 35 km/hr in a northern direction, then you would have an arrow pointing north with a length of 35. Physicists would say that the velocity is 35 km/hr north.

Velocity is the rate of motion in a specific direction. I’m going that-a-way at 30 kilometers per hour. My velocity is 30 kilometers per hour that-a-way. Average speed is described as a measure of distance divided by time. Velocity can be constant, or it can change (acceleration). Speed with a direction is velocity. 

Changing Your Velocity

 When velocity is changing, the word acceleration is used. Acceleration is also a vector. You speed up if the acceleration and velocity point in the same direction. You slow down (also referred to as decelerating) if the acceleration and velocity point in opposite directions. When you accelerate or decelerate, you change your velocity by a specific amount over a specific amount of time.

Constant Acceleration

There are a few special situations where acceleration may be constant. This type of acceleration happens when there is a constant net force applied. The best example is gravity. Gravity’s pull on objects is a constant here on Earth and it always pulls toward the center of the planet (Note: Gravity decreases as you move far away from the surface of the planet.). The gravities of other planets are different from Earth’s gravity because they may have different masses and/or sizes. Even though the gravity may be smaller or larger, it will still create a constant acceleration near the surface of each planet. 

Forces of Attraction

 Gravity or gravitational forces are forces of attraction. We’re not talking about finding someone really cute and adorable. It’s like the Earth pulling on you and keeping you on the ground. That pull is gravity at work.

Every object in the universe that has mass exerts a gravitational pull, or force, on every other mass. The size of the pull depends on the masses of the objects. You exert a gravitational force on the people around you, but that force isn’t very strong, since people aren’t very massive. When you look at really large masses, like the Earth and Moon, the gravitational pull becomes very impressive. The gravitational force between the Earth and the molecules of gas in the atmosphere is strong enough to hold the atmosphere close to our surface. Smaller planets, that have less mass, may not be able to hold an atmosphere.

Planetary Gravity

Obviously, gravity is very important on Earth. The Sun’s gravitational pull keeps our planet orbiting the Sun. The motion of the Moon is affected by the gravity of the Sun AND the Earth. The Moon’s gravity pulls on the Earth and makes the tides rise and fall every day. As the Moon passes over the ocean, there is a swell in the sea level. As the Earth rotates, the Moon passes over new parts of the Earth, causing the swell to move also. The tides are independent of the phase of the moon. The moon has the same amount of pull whether there is a full or new moon. It would still be in the same basic place.

We have to bring up an important idea now. The Earth always produces the same acceleration on every object. If you drop an acorn or a piano, they will gain velocity at the same rate. Although the gravitational force the Earth exerts on the objects is different, their masses are just as different, so the effect we observe (acceleration) is the same for each. The Earth’s gravitational force accelerates objects when they fall. It constantly pulls, and the objects constantly speed up.

They Always ask About Feathers

 People always say, “What about feathers? They fall so slowly.” Obviously, there is air all around us. When a feather falls, it falls slowly because the air is in its way. There is a lot of air resistance and that resistance makes the feather move slower. The forces at work are the same. If you dropped a feather in a container with no air (a vacuum), it would drop as fast as a baseball.

What About the Moon?

But what keeps the Moon from falling down, if all of this gravity is so strong? Well, the answer is that the moon IS falling; all the time, but doesn’t get any closer to us! Remember that if there wasn’t a force acting, the Moon would be travelling in a straight line. Because there IS a force of attraction toward the Earth, the moon “falls” from a straight line into a curve (orbit) around the Earth and ends up revolving around us.

Friction Basics

 Friction is a force that holds back the movement of a sliding object. That’s it. Friction is just that simple.

You will find friction everywhere that objects come into contact with each other. The force acts in the opposite direction to the way an object wants to slide. If a car needs to stop at a stop sign, it slows because of the friction between the brakes and the wheels. If you run down the sidewalk and stop quickly, you can stop because of the friction between your shoes and the cement.

What happens if you run down the sidewalk and you try to stop on a puddle? Friction is still there, but the liquid makes the surfaces smoother and the friction a lot less. Less friction means it is harder to stop. The low friction thing happens to cars when it rains. That’s why there are often so many accidents. Even though the friction of the brakes is still there, the brakes may be wet, and the wheels are not in as much contact with the ground. Cars hydroplane when they go too fast on puddles of water.

Friction and Gases

 Friction only happens with solid objects, but you do get resistance to motion in both liquids and gases. This doesn’t involve sliding surfaces like friction does, but is instead the kind of resistance you get if you try to push your way through a crowd. It’s a colliding situation, not a sliding one. If the gas is air, this is referred to as air resistance.

If you were in the space shuttle and re-entering the atmosphere, the bottom of the shuttle would be getting very hot. The collisions that occur between the molecules of the air being compressed by the shuttle, heat up the air AND the shuttle itself. The temperature on the top of the shuttle is also warm, but nowhere near the temperatures found on the bottom.

Friction and Liquids

Although liquids offer resistance to objects moving through them, they also smooth surfaces and reduce friction. Liquids tend to get thinner (less viscous) as they are heated. Yes, that’s like the viscosity of the oil you put in your car. Car engines have a lot of moving parts, and they rub on each other. The rubbing produces friction and the result is heat. When oil is added to a car engine, the oil sticks to surfaces, and helps to decrease the amount of friction and wear on the parts of the engine. An engine that runs hotter requires a more viscous oil in order for it to stick to the surfaces properly.

 -Finally, here you will find three funny activities about motion and forces, and a video about the effects of Moon on tides.



Discover a lot of inventions!

Around 1750, the first glue or adhesive patent was issued in Britain. The glue was made from fish. Patents were then rapidly issued for adhesives using natural rubber, animal bones, fish, starch, milk protein or casein.
Scotch tape was invented in 1930 by banjo playing 3M engineer Richard Drew. Scotch tape was the world’s first transparent adhesive tape. Richard Drew also invented the first masking tape in 1925, a two-inch-wide tan paper tape with a pressure sensitive adhesive backing.
The baby carriage was invented in 1733 by English architect William Kent for the 3rd Duke of Devonshire’s children.

A Hungarian journalist named Laszlo Biro invented the first ballpoint pen in 1938. Biro had noticed that the type of ink used in newspaper printing dried quickly, leaving the paper dry and smudge-free. He decided to create a pen using the same type of ink. The thicker ink would not flow from a regular pen nib and Biro had to devise a new type of point. He did so by fitting his pen with a tiny ball bearing in its tip. As the pen moved along the paper, the ball rotated picking up ink from the ink cartridge and leaving it on the paper.

 The first rubber balloons were made by Professor Michael Faraday in 1824 for use in his experiments with hydrogen at the Royal Institution in London.

 Earle Dickson was employed as a cotton buyer for the Johnson & Johnson when he invented the band-aid in 1921. His wife Josephine Dickson was always cutting her fingers in the kitchen while preparing food.

What is bar code? It is method of automatic identification and data collection. The first patent for a bar code type product was issued to inventors Joseph Woodland and Bernard Silver on October 7, 1952. The Woodland and Silver bar code can be described as a “bull’s eye” symbol, made up of a series of concentric circles.

A barometer is an instrument for measuring atmospheric pressure. Two common types are the aneroid barometer and the mercurial barometer (invented first). Evangelista Torricelli invented the first barometer, known as the “Torricelli’s tube”.

In 1800 Alessandro Volta invented the voltaic pile and discovered the first practical method of generating electricity. Constructed of alternating discs of zinc and copper with pieces of cardboard soaked in brine between the metals, the voltic pile produced electrical current. The metallic conducting arc was used to carry the electricity over a greater distance. Alessandro Volta’s voltaic pile was the first “wet cell battery” that produced a reliable, steady current of electricity. 

Some history books will state that Pierre and Ernest Michaux, the French father and son team of carriage-makers, invented the first bicycle during the 1860s. Historians now disagree and there is evidence that the bicycle is older than that. However, historians do agree that Ernest Michaux did invent the modern bicycle pedal and cranks in 1861.

In 1853 Levi Strauss, a 24-year-old German immigrant, had the canvas made into waist overalls. Miners liked the pants, but complained that they tended to chafe. Levi Strauss substituted a twilled cotton cloth from France called “serge de Nimes.” The fabric later became known as denim and the pants were nicknamed blue jeans.

The first modern brassiere to receive a patent was the one invented in 1913 by a New York socialite named Mary Phelps Jacob.

Braille, a system of raised dots that is read with the fingers, has historically been embossed on paper. The system was invented by Louis Braille of France in the early 1800s.

In 1577, Jost Burgi invented the minute hand. Burgi’s invention was part of a clock made for Tycho Brahe, an astronomer who needed an accurate clock for his stargazing. In 1656, the pendulum was invented by Christian Huygens, making clocks more accurate.

In 1885, Burroughs filed his first patent for a calculating machine. However, his 1892 patent was for an improved calculating machine with an added printer. William Seward Burroughs invented the first practical adding and listing machine.

Canadian John Hopps invented the first cardiac pacemaker. Hopps was trained as an electrical engineer at the University of Manitoba and joined the National Research Council in 1941, where he conducted research on hypothermia. While experimenting with radio frequency heating to restore body temperature, Hopps made an unexpected discovery: if a heart stopped beating due to cooling, it could be started again by artificial stimulation using mechanical or electric means.

Karl Benz, the German mechanical engineer who designed and in 1885 built the world’s first practical automobile, and Henry Ford, who improved the assembly line for automobile manufacturing and invented a car transmission mechanism, can be considered the inventors of cars.

April 3, 2003 marked the 30th anniversary of the first public telephone call placed on a portable cellular phone. Martin Cooper  placed that call on April 3, 1973, while general manager of Motorola’s Communications Systems Division.

Invented around 1690, the clarinet is a single-reed woodwind instrument with a cylindrical tube. The clarinet evolved from an earlier instrument called the chalumeau, the first true single reed instrument. Johann Christoph Denner of Nuremburg with the help of his son Jacob improved the chalumeau, creating a new instrument called the clarinet.

In May, 1886, Coca Cola was invented by Doctor John Pemberton a pharmacist from Atlanta, Georgia. John Pemberton concocted the Coca Cola formula in a three legged brass kettle in his backyard. The name was a suggestion given by John Pemberton’s bookkeeper Frank Robinson.

James Russell invented the compact disk in 1965. James Russell was granted a total of 22 patents for various elements of his compact disk system. However, the compact disk did not become popular until it was mass manufactured by Philips in 1980.

 The first person recorded to have used the compass as a navigational aid was Zheng He (1371-1435), from the Yunnan province in China, who made seven ocean voyages between 1405 and 1433.

  Adolph Fick first thought of making glass contact lenses in 1888, but it took until 1948 when Kevin Tuohy invented the soft plastic lens for contacts to become a reality.

Nitroglycerin was first invented by Italian chemist Ascanio Sobrero in 1846. In its natural liquid state, nitroglycerin is very volatile. Albert Nobel understood this and in 1866 he discovered that mixing nitroglycerine with silica would turn the liquid into a malleable paste, called dynamite. One advantage of dynamite over nitroglycerin was that it could be cylinder-shaped for insertion into the drilling holes used for mining.

Gustave Eiffel built the Eiffel Tower for the Paris World’s Fair of 1889, which honored the 100th anniversary of the French Revolution. The World’s Fair or Universal Exposition of 1889 (Exposition Universelle de 1889) was a highly successful international exhibition and one of the few world’s fairs to make a profit. Its central attraction was the Eiffel Tower, a 300-meter high marvel of iron by Gustave Eiffel.

Electricity: Beginning with Benjamin Franklin’s experiment with a kite one stormy night in Philadelphia, the principles of electricity gradually became understood. In the mid-1800s, everyone’s life changed with the invention of the electric light bulb. Prior to 1879, electricity had been used in arc lights for outdoor lighting. The lightbulb’s invention used electricity to bring indoor lighting to our homes.

Computer engineer, Ray Tomlinson invented internet based  in email late 1971. Under ARPAnet several major innovations occurred: email (or electronic mail), the ability to send simple messages to another person across the network (1971).

The guitar is considered a European-invented instrument that first appeared during the medievel period. The form of the modern classical guitar is credited to Spanish guitar maker Antonio Torres circa 1850. Torres increased the size of the guitar body, altered its proportions, and invented the “fan” top bracing pattern. Antonio Torres’ design greatly improved the volume, tone, and projection of the instrument, and has remained essentially unchanged.

During the mid 1500′s, Italian inventor Leonardo Da Vinci made drawings of an ornithopter flying machine that some experts say inspired the modern day helicopter. In 1784, French inventor, Launoy and Bienvenue created a toy with a rotary-wing that could lift and fly and proved the principle of helicopter flight.

Forms of intravenous injection and infusion began as early as 1670. However, Charles Gabriel Pravaz and Alexander Wood were the first to develop a syringe with a needle fine enough to pierce the skin in 1853.

On June 6, 1882, Henry W. Seely of NYC patented the electric iron, at the time it was called the electric flatiron. Early electric irons used a carbon arc to create heat, however, this was not a safe method. In 1892, hand irons using electrical resistance were introduced by Crompton and Co. and the General Electric Company. During the early 1950s electric steam irons were introduced. 

Incandescent lightbulbs work in this way: electricity flows through the filament that is inside the bulb; the filament has resistance to the electricity; the resistance makes the filament heat to a high temperature; the heated filament then radiates light. All incandescent lamps work by using a physical filament. Thomas A. Edison’s lamp became the first commercially successful incandescent lamp (circa 1879). Incandescent lamps are still in regularly use in our homes, today.

In 1827, John Walker, English chemist and apothecary, discovered that if he coated the end of a stick with certain chemicals and let them dry, he could start a fire by striking the stick anywhere. These were the first friction matches.

About 1590, two Dutch spectacle makers, Zaccharias Janssen and his son Hans, while experimenting with several lenses in a tube, discovered that nearby objects appeared greatly enlarged. That was the forerunner of the compound microscope and of the telescope. In 1609, Galileo, father of modern physics and astronomy, heard of these early experiments, worked out the principles of lenses, and made a much better instrument with a focusing device.

While a professor of arts and design at New York University in 1835, Samuel Morse proved that signals could be transmitted by wire. He used pulses of current to deflect an electromagnet, which moved a marker to produce written codes on a strip of paper – the invention of Morse Code. The following year, the device was modified to emboss the paper with dots and dashes. He gave a public demonstration in 1838, but it was not until five years later that Congress (reflecting public apathy) funded $30,000 to construct an experimental telegraph line from Washington to Baltimore, a distance of 40 miles.

The Pasteur Institute was opened in 1888. During Louis Pasteur’s lifetime it was not easy for him to convince others of his ideas, controversial in their time but considered absolutely correct today. Pasteur fought to convince surgeons that germs existed and carried diseases, and dirty instruments and hands spread germs and therefore disease. Pasteur’s pasteurization process killed germs and prevented the spread of disease.

In 1928, Sir Alexander Fleming observed that colonies of the bacterium Staphylococcus aureus could be destroyed by the mold Penicillium notatum, proving that there was an antibacterial agent there in principle. This principle later lead to medicines that could kill certain types of disease-causing bacteria inside the body.  At the time, however, the importance of Alexander Fleming’s discovery was not known. Use of penicillin did not begin until the 1940s when Howard Florey and Ernst Chain isolated the active ingredient and developed a powdery form of the medicine.

The piano first known as the pianoforte evolved from the harpsichord around 1700 to 1720, by Italian inventor Bartolomeo Cristofor. Harpsichord manufacturers had been determined to produce an instrument with a better dynamic response than the harpsichord. Bartolomeo Cristofali, the keeper of instruments in the court of Prince Ferdinand de Medici of Florence, was the first to solve the problem.

Guglielmo Marconi, an Italian inventor, proved the feasibility of radio communication. He sent and received his first radio signal in Italy in 1895. By 1899 he flashed the first wireless signal across the English Channel and two years later received the letter “S”, telegraphed from England to Newfoundland. This was the first successful transatlantic radiotelegraph message in 1902.

The Statue of Liberty arrived in New York Harbor on June 19, 1885. The monument was a gift of friendship from the people of France to the people of the United States, intended to commemorate the centennial of the American Declaration of Independence, some ten years earlier. Sculptor Frederic Auguste Bartholdi’s Statue of Liberty enlightening the world stands more than 300 feet high.  French historian Edouard Laboulaye suggested the presentation of this statue to the United States, commemorating the alliance of France and the United States during the American Revolution. The copper colossus was designed by Frederic Auguste Bartholdi and erected according to plans by Gustave Eiffel.

In the 1870s, two inventors Elisha Gray and Alexander Graham Bell both independently designed devices that could transmit speech electrically (the telephone). Both men rushed their respective designs to the patent office within hours of each other, Alexander Graham Bell patented his telephone first. Elisha Gray and Alexander Graham Bell entered into a famous legal battle over the invention of the telephone, which Bell won.

In the 1920′s, John Logie Baird patented the idea of using arrays of transparent rods to transmit images for television. Baird’s 30 line images were the first demonstrations of television by reflected light rather than back-lit silhouettes.

The first thermometers were called thermoscopes and while several inventors invented a version of the thermoscope at the same time, Italian inventor Santorio Santorio was the first inventor to put a numerical scale on the instrument. Galileo Galilei invented a rudimentary water thermometer in 1593 which, for the first time, allowed temperature variations to be measured. In 1714, Gabriel Fahrenheit invented the first mercury thermometer, the modern thermometer.

On 8 Nov, 1895, Wilhelm Conrad Röntgen (accidentally) discovered an image cast from his cathode ray generator, projected far beyond the possible range of the cathode rays (now known as an electron beam). Further investigation showed that the rays were generated at the point of contact of the cathode ray beam on the interior of the vacuum tube, that they were not deflected by magnetic fields, and they penetrated many kinds of matter. A week after his discovery, Rontgen took an X-ray photograph of his wife’s hand which clearly revealed her wedding ring and her bones. The photograph electrified the general public and aroused great scientific interest in the new form of radiation. Röntgen named the new form of radiation X-radiation (X standing for “Unknown”). Hence the term X-rays (also referred as Röntgen rays, though this term is unusual outside of Germany).

-Finally, enjoy these videos about famous inventors! (Louis Braille) (The greatest American Inventions) (Leonardo Da Vinci) (Thomas A. Edison) (Galileo Galilei) (Samuel Morse) (Alexander Fleming)


Machines are devices that help people to do tasks. We have to distinguish between simple and complex machines.

A simple machine is a device that helps make work easier; a device that makes it easier to move something. Some simple machines are a wheel, a pulley, a lever, a screw, and an inclined plane. Most machines consist of a number of elements, such as gears and ball bearings, that work together in a complex way. No matter how complex a machine, it is still based on the compounding of six types of simple machines. The six types of machines are the lever, the wheel and axle, the pulley, the inclined plane, the wedge, and the screw.

-A pulley is a simple machine that uses grooved wheels and a rope to raise, lower or move a load.

-A lever is a stiff bar that rests on a support called a fulcrum which lifts or moves loads.

 -A wedge is an object with at least one slanting side ending in a sharp edge, which cuts material apart.

-A wheel with a rod, called an axle, through its center lifts or moves loads.

-An inclined plane is a slanting surface connecting a lower level to a higher level.

-A screw is an inclined plane wrapped around a pole which holds things together or lifts materials.

A Complex Machine  is a system in which simple machines all work together, parts of a complex machine that have just one function are called subsystems and often contain a simple machine.

-Finally, do the following activities. You’ll find them very interesting!


When two or more substances are mixed together but not chemically joined they are called as mixtures.

Mixtures are absolutely everywhere you look. Mixtures form for most things in nature. Rocks, air, or the ocean, they are just about anything you find. They are substances held together by physical forces, not chemical. This statement means that the individual molecules enjoy being near each other, but their fundamental chemical structure does not change when they enter the mixture.

The methods of separation of mixtures depend on the constituents of the mixtures.

The constituents in a mixture can be separated by easy methods like picking, sieving, or winnowing. You can make a mixture of rice, paper, clips and marbles. These can be separated into different piles of rice, paper, clips and marbles. Some mixtures can be separated by evaporation or condensation.

Mixtures can be categorized as heterogeneous or homogeneous. Heterogeneous mixtures do not appear to be the same throughout. Concrete, conglomerate rock, as well as oil and vinegar are all heterogeneous mixtures. The particles are large enough to be seen and can be separated from the mixture.

Homogeneous mixtures are very well mixed. A salt solution is a homogeneous mixture. In a solution, one substance is dissolved in another. The particles in a solution are atoms, ions, or molecules. The particles are obviously too small to be seen and will not separate out on standing, but can be separated by the process of evaporation.

Solutions : Have you ever put sugar in a glass of milk? After you stir, you can no longer see the sugar. The sugar is still there, as you can taste it. A mixture of sugar and milk is called as solution. By evaporation we can separate the different kinds of matter in solution.

Physical changes: Matter undergoes changes. Changes in matter, in which no new substances are formed are called as physical changes. Changes in temperature can make matter look different. Cooling makes liquid water change to ice.

The ice has the same particles, the liquid water has. It can be reverted back to water by melting. Here no new substances are formed. So it is a physical change.

Chemical changes : Matter undergoes changes. Some changes produce new substances. Such changes are called as chemical changes. When wood burns, it combines with the oxygen in air and forms smoke and ash.

You notice an orange brown coating on things made of iron when they come in contact with moisture. This is called as rust. Rusting is a chemical change.

-Finally, enjoy the following videos about mixtures and solutions!

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