Question

What is precession of the equinoxes?

Answer 1

The precession of equinoxes is attributed to the revolution of Earth's polar axis, with period 258 centuries, nearly, about a mean position that is perpendicular to Earth's orbital plane ( ecliptic).

Explanation:

In this precession with Great Year period of 258 centuries, the poles describe a circle of angular diameter `46.8^o`, nearly, up on the Earth

Corresponding to this axial precession, the location for the right-above-head noon, at the equinox instant, shifts the equinoxes (common points of the ecliptic and the Earth's equator) towards north by #360^o, in 258 centuries.

Corresponding time-rate is approximately (24 X 3600)/(25800)"/year = 3.35 sec/year.

Importantly, the tilt angle `23.4^o` of the axis to the normal of the ecliptic is unchanged,