The Celestial Equator

The *Celestial Equator* is an imaginary great circle on the celestial sphere. The celestial equator
is the fundamental plane of the Equatorial
Coordinate System, so it is defined as the locus of points
with Declination of zero degrees. It is also the projection of the
Earth's equator onto the sky.

The Celestial Equator and the Ecliptic are set at an angle of 23.5 degrees in the sky. The points where they intersect are the Vernal and Autumnal Equinoxes.