Equinox: now speeding it, and again retarding it

DefinitionThis historical phrase describes the true equinox moving alternately ahead of and behind its mean position. The effect is chiefly associated with...

Plane

DefinitionIn astrology, a plane is either a geometric reference surface used to map celestial positions or, in some esoteric traditions, a level...

However, the Ecliptic plane is not fixed

DefinitionThe ecliptic plane is the geometric plane of Earth’s orbit around the Sun and the basis for the apparent annual path of...

Precession is 25,694.8 years

DefinitionPrecession is the gradual change in the orientation of Earth’s rotational axis, caused mainly by the gravitational influence of the Sun and...

Secular perturbation

DefinitionSecular perturbation is an astronomical term for a slow, cumulative change in a celestial body’s orbit caused mainly by the gravitational influence...