Polar circles

Related to Polar circles: Arctic Circle
(Astron. & Geog.) two circles, each at a distance from a pole of the earth equal to the obliquity of the ecliptic, or about 23° 28´, the northern called the arctic circle, and the southern the antarctic circle.

See also: Polar

References in classic literature ?
He showed me also, in one of his books, the figures of the sun, moon, and stars, the zodiac, the tropics, and polar circles, together with the denominations of many plains and solids.
Now if we look at a globe, we shall see that under the Polar Circle there is almost continuous land from western Europe, through Siberia, to eastern America.
During the slowly decreasing warmth of the Pliocene period, as soon as the species in common, which inhabited the New and Old Worlds, migrated south of the Polar Circle, they must have been completely cut off from each other.
As on the land, so in the waters of the sea, a slow southern migration of a marine fauna, which during the Pliocene or even a somewhat earlier period, was nearly uniform along the continuous shores of the Polar Circle, will account, on the theory of modification, for many closely allied forms now living in areas completely sundered.
THE man who's seen the world's seven wonders, set foot on all seven continents and crossed both polar circles is now going to go face to face with the world's highest mountain - Everest.
People outside polar circles do not really know anything about him.
HE'S already seen the world's seven wonders, now he's set foot on all seven continents and crossed both polar circles and all before turning 50.
The Marton school has been focusing on the wilds of the jungle through to the harsh conditions of the earth's polar circles.