arctic circle

Proper noun capitalized: Arctic Circle

the Arctic Circle

1. The parallel of latitude that runs 66° 33′ 39″ north of the Equator, which marks approximately the southernmost place in the Northern Hemisphere where the sun does not set on the summer solstice and does not rise on the winter solstice.
   • PYTHAGORAS saith, that the earth is divided into five Zones proportionably to the sphaere of the universall heaven; to wit, the Artick circle, the Tropick of Summer, the Tropick of Winter, the Aequinoctiall and the Antartick.1603, Philemon Holland (translator), The Philosophie, commonlie called, the Morals written by the Learned Philosopher Plutarch of Chæronea, London, The Opinions of the Philosophers, Book 3, Chapter...
   • Then he tells us that the Bear, or Stars of the Arctick Circle, never disappear; as an Observation which agrees with no other.1715, Alexander Pope, “An Essay on the Life, Writings and Learning, of Homer”, in The Iliad of Homer, London: Bernard Lintott, page 51