circumpolar

Circumpolar is a term used in astronomy and geography to describe things that are around or near a pole, either the Earth’s geographic poles or the celestial poles. It is also used to refer to regions that lie close to the poles and to objects that appear to circle around a pole.

In astronomy, a circumpolar object is one that never sets below the horizon for a given observer. Whether a star or a constellation is circumpolar depends on the observer’s latitude. The condition is roughly that the star’s declination must be high enough to remain above the horizon all the time. For example, near the North Pole many northern stars stay visible year-round, while near the equator no stars are circumpolar. Common northern circumpolar constellations include Ursa Major, Ursa Minor, Cassiopeia, and Cepheus, viewed in appropriate latitudes.

In geography, circumpolar regions lie near the poles within the Arctic Circle in the north and the Antarctic Circle in the south. These areas experience extreme photoperiods, including polar day (continuous daylight) in summer and polar night in winter. The climate is cold, and ecosystems are adapted to ice, snow, and strong winds. Human activity is concentrated in the Arctic regions, with indigenous communities and research stations; the Antarctic interior is largely uninhabited and used mainly for science.

The term derives from Latin circum, around, and polaris, pole, and is used across disciplines to denote proximity to or circulation around a pole.