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Arctic Circle

(Encyclopedia)Arctic Circle, imaginary circle on the surface of the earth at 66 12°N latitude, i.e., 23 12° south of the North Pole. It marks the northernmost point at which the sun can be seen at the win...

Arctic Council

(Encyclopedia)Arctic Council, intergovernmental forum established to promote cooperation, coordination, and interaction among the arctic nations, with the involvement of indigenous peoples and others inhabiting the...

Arctic, the

(Encyclopedia)Arctic, the northernmost area of the earth, centered on the North Pole. The arctic regions are not coextensive with the area enclosed by the Arctic Circle (lat. 66°30N) but are usually defined by ...

circle

(Encyclopedia)circle, closed plane curve consisting of all points at a given distance from some fixed point, called the center. A circle is a conic section cut by a plane perpendicular to the axis of the cone. The ...

Arctic Ocean

(Encyclopedia)Arctic Ocean, the smallest ocean, c.5,400,000 sq mi (13,986,000 sq km), located entirely within the Arctic Circle and occupying the region around the North Pole. Oceanography and Environment Nearly la...

Arctic Archipelago

(Encyclopedia)Arctic Archipelago ärk´tk, är´tk [key], group of more than 50 large islands, Northwest Territories and Nunavut, N Canada, in the Arctic Ocean. The southernmost members of the group include Baf...

vertical circle

(Encyclopedia)vertical circle, in astronomy, the great circle on the celestial sphere that passes from the observer's zenith through a given celestial body. In the altazimuth coordinate system the altitude of a bod...

diurnal circle

(Encyclopedia)diurnal circle dûr´nl [key], apparent path followed by a star due to the earth's rotation on its axis. The stars appear to move on the celestial sphere in concentric circular paths centered at t...

meridian circle

(Encyclopedia)meridian circle: see transit instrument.

Antarctic Circle

(Encyclopedia)Antarctic Circle, imaginary circle on the surface of the earth at 66 12°S lat., i.e., 23 12° north of the South Pole. It marks the southernmost point at which the sun can be seen at the wint...