Hipparchus c.120 B.C. The precession is due to the gravitational attraction of the moon and sun on the equatorial bulge of the earth, which causes the earth's axis to describe a cone in somewhat the same fashion as a spinning top. The equinoxes, which lie at the intersections of the celestial equator and the ecliptic, thus move on the celestial sphere. After a period of about 26,000 years the equinoxes and poles lie once again at nearly the same points on the celestial sphere.
Planetary precession is much less than luni-solar precession.
The precession of the equinoxes was first explained by Isaac Newton in 1687. Listing from Electric Library , a pay service. Copyright 2001 Infonautics Corporation . All rights reserved. The shadow of evolutionary thinking.