Seen from the equator the celestial North Pole ("boreios polos") is a point on the horizon. As the observer moves northward the pole rises and the circumpolar stars appear, now unblocked by the Earth. At the Tropic of Cancer the radius of the circumpolar stars reaches 24°. The edge stands on the horizon. The constellation of "mikra arktos" (Ursa Minor, "little bear") was entirely contained within the circumpolar region. The latitude was therefore called the "arktikos kuklos", "circle of the bear". The terrestrial Arctic Circle was regarded as fixed at this latitude. The celestial Arctic Circle was regarded as identical to the circumference of the circumpolar stars and therefore a variable.