Antarctica Europe Pacific Ocean Indian Ocean Atlantic Ocean Arctic Ocean

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    Antarctica

    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.[2] Antarctica is considered a desert,

    with annual precipitation of only 200 mm (8 inches) along the coast and far less

    inland.[3] 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 Fabian Gottlieb von

    Bellingshausen and Mikhail Lazarev. 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 name Antarctica means opposite to the north".[5]

    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. Ongoingexperiments are conducted by more than 4,000 scientists of many nationalities and

    with various research interests.[1]

    Europe

    Europe is 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 region (Specification

    of borders) and the Black Sea to the southeast.[2] Europe is bordered by the Arctic

    Ocean and other bodies of water to the north, the Atlantic Ocean to the west, the

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    Mediterranean Sea to the south, and the Black Sea and connected waterways to the

    southeast. Yet the borders for Europea 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 (although the country covers both Europe and Asia),

    while the 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.

    Europe, in particular Ancient Greece, is the birthplace of Western culture.[3] It played

    a predominant role in global affairs from the 16th century onwards, especially after

    the beginning of colonialism. Between the 16th and 20th centuries, European nations

    controlled at various times the Americas, most of Africa, Oceania, and large portions

    of Asia. Both World Wars were largely focused upon Europe, greatly contributing to

    a decline in Western European dominance in world affairs by the mid-20th century as

    the United States and Soviet Union took prominence.[4] During the Cold War, Europe

    was divided along the Iron Curtain between NATO in the west and the Warsaw Pact

    in the east. European integration led to the formation of the Council of Europe and the

    European Union in Western Europe, both of which have been expanding eastward

    since the fall of the Soviet Union in 1991.

    Pacific Ocean

    The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the

    Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australiain the west, and the Americas in the east.

    At 169.2 million square kilometres (63.8 million square miles) in area, this largest

    division of the World Ocean and, in turn, the hydrosphere covers about 46% of the

    Earth's water surface and about 30% of its total surface.[1] The equator subdivides it

    into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the

    Galpagos and Gilbert Islands, while straddling the equator, are deemed wholly

    within the South Pacific.[2] The Mariana Trench in the western North Pacific is the

    deepest point in the Pacific and in the world, reaching a depth of 10,911 metres

    (35,797 ft).[3]

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    The Pacific Ocean was sighted by Europeans early in the 16th century, first by the

    Spanish explorer Vasco Nez de Balboa who crossed the Isthmus of Panama in 1513

    and named it Mar del Sur (South Sea). Its current name was given by Portuguese

    explorer Ferdinand Magellan during the Spanish expedition of world

    circumnavigation in 1521, who encountered calm seas during the journey and called it

    Tepre Pacificum in Latin, meaning "pacific" or "peaceful sea".[4]

    Indian Ocean

    The Indian Ocean is the third largest of the world's oceanic divisions, covering about

    20% of the water on the Earth's surface.[1] It is bounded on the north by the Indian

    subcontinent; on the west by East Africa; on the east by Indochina, the Sunda Islands,

    and Australia; and on the south by the Southern Ocean (or, depending on definition,

    by Antarctica). It is the only ocean to be named after a country, i.e., India.[2][3][4]

    As one component of the interconnected global ocean, the Indian Ocean is delineated

    from the Atlantic Ocean by the 20 east meridian running south from Cape Agulhas,

    and from the Pacific by the meridian of 14655' east[5]. The northernmost extent of

    the Indian Ocean is approximately 30 north in the Persian Gulf. The Indian Ocean

    has asymmetric ocean circulation[citation needed]. This ocean is nearly 10,000

    kilometres (6,200 mi) wide at the southern tips of Africa and Australia; its area is

    73,556,000 square kilometres (28,400,000 mi2), including the Red Sea and the

    Persian Gulf.

    The ocean's volume is estimated to be 292,131,000 cubic kilometres (70,086,000

    mi3).[6] Small islands dot the continental rims. Island nations within the ocean are

    Madagascar, the world's fourth largest island; Reunion Island; Comoros; Seychelles;

    Maldives; Mauritius; and Sri Lanka. The archipelago of Indonesia borders the ocean

    on the east.

    Atlantic Ocean

    The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total

    area of about 106,400,000 square kilometres (41,100,000 sq mi), it covers

    approximately twenty percent of the Earth's surface and about twenty-six percent of

    its water surface area. The first part of its name refers to Atlas of Greek mythology,

    making the Atlantic the "Sea of Atlas".

    The oldest known mention of "Atlantic" is in The Histories of Herodotus around 450

    BC (Hdt. 1.202.4): Atlantis thalassa (Greek: ; English: Sea of

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    Atlas); see also: Atlas Mountains. Another name historically used was the ancient

    term Ethiopic Ocean, derived from Ethiopia, whose name was sometimes used as a

    synonym for all of Africa and thus for the ocean. Before Europeans discovered other

    oceans, the term "ocean" itself was synonymous with the waters beyond the Strait of

    Gibraltar that we now know as the Atlantic. The Greeks believed this ocean to be a

    gigantic river encircling the world.

    The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally

    between the Americas to the west, and Eurasia and Africa to the east. As one

    component of the interconnected global ocean, it is connected in the north to the

    Arctic Ocean (which is sometimes considered a sea of the Atlantic), to the Pacific

    Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in

    the south. (Other definitions describe the Atlantic as extending southward to

    Antarctica.) The equator subdivides it into the North Atlantic Ocean and South

    Atlantic Ocean.

    Arctic Ocean

    The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north

    polar region, is the smallest, and shallowest of the world's five major oceanic

    divisions.[1] The International Hydrographic Organization (IHO) recognizes it as an

    ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply

    the Arctic Sea, classifying it as one of the mediterranean seas of the Atlantic Ocean.

    [2] Alternatively, the Arctic Ocean can be seen as the northernmost lobe of the all-

    encompassing World Ocean.

    Almost completely surrounded by Eurasia and North America, the Arctic Ocean is

    partly covered by sea ice throughout the year[3] (and almost completely in winter).

    The Arctic Ocean's temperature and salinity vary seasonally as the ice cover melts andfreezes;[4] its salinity is the lowest on average of the five major oceans, due to low

    evaporation, heavy freshwater inflow from rivers and streams, and limited connection

    and outflow to surrounding oceanic waters with higher salinities. The summer

    shrinking of the ice has been quoted at 50%.[1] The National Snow and Ice Data

    Center (NSIDC) uses satellite data to provide a daily record of Arctic sea ice cover

    and the rate of melting compared to an average period and specific past years.

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