POLE STAR, or POLARIS. The nearest con• spicuous star to the north pole of the heavens. The second-magnitude star whieh at the present time goes under the name of Pole star is the star a in the constellation of Ursa Minor. By examin ing attentively the movements of the stars throughout a clear night, we observe that they. describe circles which are largest for stars near the celestial equator, and beconw smaller and smalFw as we approach a certain point (the north pole), close to which is the star above men tioned. The Pole star• is, however, a little less than 1 V.° from the pole, and has a small hut sensible motion around it. (See POLE.) Owing to the motion of the pole of the heavens around the pole of the ecliptic (see PREcEsstoN), this star will in course of time (about 2100) approach to within 2S' from the north pole, and will then recede from it. At the time of Ilipparellus (p.c.
150) it was 12°, and in 178 2° from the north pole. Its place can easily be found in the (ins, for a line drawn between the stars a and g the two pointers. from this peculiarity) of the constellation Ursa Major or the Croat Bear, and produced northward for about 4V.; times its own length will almost touelt the Pole star. Two thousand years ago the star /1 of Ursa Minor was the Pole star; and about 2300 years before the Christian Era the star a in the eonstellation of the Dragon was not more than 10' front the north polo: while about 12,000 yentS from now the bright star. Vega in Lyra will he within 5° of it.
The south pole of the heavens is not similarly marked by the neighborhood of a bright star. though there is a small telescopic star very close to it.