<P> Due to the precession of the equinoxes (as well as the stars' proper motions), the role of North Star has passed (and will pass) from one star to another in the remote past (and in the remote future). In 3000 BC, the faint star Thuban in the constellation Draco was the North Star . At magnitude 3.67 (fourth magnitude) it is only one - fifth as bright as Polaris, and today it is invisible in light - polluted urban skies . </P> <P> During the 1st millennium BC, Beta Ursae Minoris ("Kochab") was the bright star closest to the celestial pole, but it was never close enough to be taken as marking the pole, and the Greek navigator Pytheas in ca . 320 BC described the celestial pole as devoid of stars . In the Roman era, the celestial pole was about equally distant between Polaris and Kochab . </P> <P> The precession of the equinoxes takes about 25,770 years to complete a cycle . Polaris' mean position (taking account of precession and proper motion) will reach a maximum declination of + 89 ° 32'23 ", which translates to 1657" (or 0.4603 °) from the celestial north pole, in February 2102 . Its maximum apparent declination (taking account of nutation and aberration) will be + 89 ° 32'50.62 ", which is 1629" (or 0.4526 °) from the celestial north pole, on 24 March 2100 . </P> <P> Precession will next point the north celestial pole at stars in the northern constellation Cepheus . The pole will drift to space equidistant between Polaris and Gamma Cephei ("Errai") by 3000 AD, with Errai reaching its closest alignment with the northern celestial pole around 4200 AD . Iota Cephei and Beta Cephei will stand on either side of the northern celestial pole some time around 5200 AD, before moving to closer alignment with the brighter star Alpha Cephei ("Alderamin") around 7500 AD . </P>

Polaris will not always be the north star. this is due to a phenomenon called