's southernmost continent
, overlying the South Pole
. It is situated in the southern hemisphere, almost entirely south of the Antarctic Circle
, and is surrounded by ocean all around i.e. the Southern Ocean
. The nearest land mass is South America
at 965 km.
Its area is close to 14 million km2, approximately 58 times the size of UK. Antarctica is the fifth largest continent after Asia, Africa, North America and South America.
Antarctica is the coldest, driest and windiest continent, and has the highest average elevation of all the continents. The minimum recorded surface temperature on the planet, −89.2 °C, was at the Soviet research station Vostok in Antarctica on 21 July 1983.
Antarctica has 98% of its total area covered by ice. The mean thickness of the ice sheet is 1829 m and the maximum thickness has been found out to be 4776 m. While most of the ice in East Antarctica is on bed rock, in West Antarctica a majority of it floats on water. Due to accumulation of ice over the past millions of years, the continent has been depressed by about 600 m on average.
Since there is little precipitation, except at the coasts, the interior of the continent is technically the largest desert in the world. There are no permanent human residents and there is no evidence of any existing or pre-historic indigenous population. Only cold-adapted plants and animals survive there, including mosses and lichens, and several species of penguins, ice seals and the Antarctic fur seals.
is a phenomenon resulting from the axial tilt
of the Earth
respective to the Sun
, where the Sun does not rise above the horizon
during any 24 hour period in the regions of the Earth in proximity to the poles
. The length of this time when the sun is constantly below the horizon varies from 20 hours at locations on the Arctic Circle
and Antarctic Circle
to 179 days at the geographic poles. The period of polar night can trigger depression
in some people. People who suffer from seasonal affective disorder
are particularly susceptible.