An Etymological Dictionary of Astronomy and Astrophysics

A → relativistic effect on the precession motion of a gravitational system due to the → curvature of the → space-time. When a body revolves around a primary, the → rotation axis of the orbiting body follows the curvature of spece-time. Over time the space-time warping causes the spin axis to precess.
In the case of the Earth-Moon system, this means a small → direct motion of the → equinox along the → ecliptic, amounting to 1’’.915 per century. The geodetic precession is given by:
ψ_g = (3/2) k² (1 - e_⊕) n_⊕, where k is the → constant of aberration (in radians), e_⊕ the → eccentricity of the Earth and n_⊕ the mean angular orbital motion of the Earth (in arcsec/cy).
Also called → Einstein-de Sitter effect and → geodesic precession.

See also: → geodetic; → precession