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the. the star closest to the N celestial pole at any particular time. At present this is Polaris, but it will eventually be replaced by some other star owing to precession of the earth's axis
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
pole starThe star closest to the north or south celestial pole at any particular time. As a result of precession the position of each pole traces out a circle in the sky in a period of about 25 800 years. There is thus a sequence of stars, including Polaris, Vega, and Thuban, that have been and will become again the northern pole star (see illustration). The nearest naked-eye star to the south celestial pole is at present the 5th magnitude star Sigma Octantis. The altitude of the pole star is approximately equal to the local latitude.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
Pole Star[′pōl ‚stär]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.