Arctic Circle

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decline in minimum Arctic sea ice extent

sunlight strikes parts of Earth differently

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Arctic Circle

Written and fact-checked by The Editors of Encyclopaedia Britannica

Last Updated: May 31, 2025 • Article History

News •

Hertfordshire golfer waits for golf marathon record confirmation • May 29, 2025, 7:25 AM ET (BBC)

British sailor set for solo loop of Arctic Circle • May 23, 2025, 5:28 AM ET (BBC)

Australian polar adventurer turned astronaut Eric Philips takes part in historic SpaceX mission • May 14, 2025, 2:47 AM ET (ABC News (Australia))

Bodø/Glimt 0-2 Tottenham Hotspur (1-5 agg): Europa League semi-final, second leg – as it happened • May 9, 2025, 10:24 AM ET (The Guardian)

Arctic Ocean

decline in minimum Arctic sea ice extent — decline in minimum Arctic sea ice extentRemote sensing has revealed the loss in Arctic sea ice extent since the late 1970s.

Arctic Circle — Arctic Circle World map with the Arctic Circle marked.

Arctic Circle, parallel, or line of latitude around Earth, at approximately 66°30′ N. Because of Earth’s inclination of about 23 1/2° to the vertical, it marks the southern limit of the area within which, for one day or more each year, the sun does not set (about June 21) or rise (about December 21). The length of continuous day or night increases northward from one day on the Arctic Circle to six months at the North Pole. The Antarctic Circle is the southern counterpart of the Arctic Circle, where on any given date conditions of daylight or darkness are exactly opposite.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Michele Metych.