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Instead, atmospheric refraction and the Sun's light reaching the planet as an extended object rather than a point source means that just within each circle the Earth's surface does not experience any proper polar night, 24 hours where the sun does not rise. By these same two factors, just outward of each circle still experiences a polar day (a ...
Midnight sun at the North Cape on the island of Magerøya in Norway. Midnight sun, also known as polar day, is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the Sun remains visible at the local midnight.
The length of polar night varies by latitude from 24 hours just inside the polar circles to 179 days at the poles. As there are various kinds of twilight, there also exist various kinds of polar twilight that progress towards true polar night. Each kind of polar night is defined as when it is darker than the corresponding kind of twilight.
A mean solar day (what we normally measure as a "day") is the average time between local solar noons ("average" since this varies slightly over a year). Earth makes one rotation around its axis each sidereal day; during that time it moves a short distance (about 1°) along its orbit around the Sun.
Antarctica sits on every line of longitude because the South Pole is on the continent. Theoretically, Antarctica would be located in all time zones; however, areas south of the Antarctic Circle experience extreme day-night cycles near the times of the June and December solstices, making it difficult to determine which time zone would be appropriate.
The Antarctic Circle is the northernmost latitude in the Southern Hemisphere at which the centre of the sun can remain continuously above the horizon for twenty-four hours; as a result, at least once each year at any location within the Antarctic Circle the centre of the sun is visible at local midnight, and at least once the centre of the sun is below the horizon at local noon.
Antarctica Day is an international holiday recognizing the anniversary of the signing of the Antarctic Treaty in 1959. It is celebrated on December 1 each year. It is celebrated on December 1 each year.
The Arctic Circle, at roughly 66.5° north, is the boundary of the Arctic waters and lands. The Arctic Circle is one of the two polar circles, and the northernmost of the five major circles of latitude as shown on maps of Earth at about 66° 34' N. [1] Its southern counterpart is the Antarctic Circle.