Polestar

Also spelled �pole star�, also called (Northern Hemisphere) �North Star� the brightest star that appears nearest to either celestial pole at any particular time. Owing to the precession of the equinoxes, the position of each pole describes a small circle in the sky over a period of 25,800 years. Each of a succession of stars has thus passed near enough to the north celestial pole to serve as the polestar. At present the polestar is Polaris; Thuban