Article
Article
Arctic Circle
Article By:
English, Van H. Department of Geography, Dartmouth College, Hanover, New Hampshire.
Last reviewed:October 2019
DOI:https://doi.org/10.1036/1097-8542.049010
The parallel of latitude approximately 66°30′ north of the Equator, or 23.5° from the North Pole. Named for the northern constellation Bear, the Arctic Circle has the same angular distance from the Equator as the inclination of the Earth's axis from the plane of the ecliptic. Thus, when the Earth in its orbit is at the Northern Hemisphere summer solstice, June 21, and the North Pole is tilted 23.5° toward the Sun, the Sun's rays extend beyond the pole 23.5° to the Arctic Circle, giving that parallel 24 h of sunlight. On this same date the Sun's rays at noon will just reach the horizon at the Antarctic Circle, 66°30′ south. The highest altitude of the noon Sun at the Arctic Circle is on June 21, when it is 47° above the horizon.
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