-slow change in the orientation of earth axis of rotation of gravity induced
-Precession cycle 26000 years discovered by Hipparchus.
Is a phenomena.
The Pole Star (Polaris) will shift after about 8,000 years
The current northpole star is Polaris, In about 8,000 years it will be the bright star Deneb, and in about 12,000 years, Vega
-axis remains constant but processes around a path such as a top slowing, points to different constellation
-one cycle= 26 000 years
-earth doesnt spin perfectly upright