L 'equador celest i l' eclíptica són dos cercles majors sobre l 'esfera celest, establerts a un angle de 23, 5 graus. Els dos punts a on interseccionen s' anomenen els equinoccis. L' equinocci de primavera té les coordenades AR=0, 0 hores, Dec=0, 0 graus. L 'equinocci de tardor té les coordenades AR=12, 0 hores, Dec=0, 0 graus.
The Celestial Equator and the Ecliptic are two Great Circles on the Celestial Sphere, set at an angle of 23.5 degrees. The two points where they intersect are called the Equinoxes. The Vernal Equinox has coordinates RA=0.0 hours, Dec=0.0 degrees. The Autumnal Equinox has coordinates RA=12.0 hours, Dec=0.0 degrees.