What is the precession of the equinoxes? Is it scientifically valid?

1 Answer
Apr 24, 2016

Annual right-above-head-noon-Sun equinoxes are antipodal locations on the equator, They move along the equator, taking about 26000 years, to go round once. This is scientifically valid.


About 12 thousand years ago, ancient astronomers had marked the star Vega as the North Pole star. Now it is Polaris. The angular spacing in-between is nearly #40^o#.

Based on this supposedly reliable information, research had revealed that there is precession-revolution of the polar axis about the normal to the ecliptic.

This normal is the axis of the double right circular cone, with vertex at the center of the Earth. The polar axis is a slant side of this double cone. The semi-vertical angle = the tilt angle #23.4^o that the axis makes with the normal.

Respectively, the precession paths of poles are around the circular sections of this cone with the surface of the Earth. .Due to nutation (nodding ) the paths are little wavy across these small circles.

The period for precession might be nearly 258 centuries, called Great Year.

The angular speed for this rotation is #(2pi)/25800# radian/year=2.435 E-04 radian/year=#0.014^o#/year=50"/year, nearly, for both the poles and the equinoxes.

All these motions are attributed to the gravitational pulls of the close by small-mass-Moon and a little far away large-mass-Sun. The orbital inclination of the Moon is also responsible. for these periodic motions.