پیشایان ِ کهینرهی pišâyân-e kehinrahi
*Fr.: précession géodésique*
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) *k*^{2} (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*. → *geodetic*; → *precession* |