An Etymological Dictionary of Astronomy and Astrophysics
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Of, relating to, or determined by → geodesy.

→ geodesy; → -ic.

A → coordinate system, composed of → geodetic latitude and → geodetic longitude on the → Earth's surface which is dependent on the figure and size of a particular model for the Earth's surface.

→ geodetic; → coordinate.

Any of the adopted values of → geodetic latitude, → geodetic longitude, or → azimuth at a selected location (an initial station) whose astronomical coordinates have already been determined.

→ geodetic; → datum.

The plane swept out as the generating ellipse of the → reference ellipsoid rotates about its minor axis.

→ geodetic; → equator.

The → acute angle between the → geodetic vertical and the → geodetic equator.

→ geodetic; → latitude.

The angle between the plane of the → geodetic meridian and the plane of of the geodetic meridian through the site of the → Airy transit circle at the Royal Greenwich Observatory.

→ geodetic; → longitude.

The → ellipse through the point in question which passes through the → geodetic poles.

→ geodetic; → meridian.

Any of the small circles on the → reference ellipsoid parallel to the → geodetic equator.

→ geodetic; → parallel.

Any of the interaction points of the axis of revolution of the → reference ellipsoid with its surface.

→ geodetic; → pole.

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.

→ geodetic; → precession

The limiting case of → astronomical refraction when the light path is entirely within the Earth's atmosphere.

→ geodetic; → refraction.

The direction defined by the → normal to the → reference ellipsoid at the point in question.

→ geodetic; → vertical.

The intersection of the prolongation of the outward → normal to the → reference ellipsoid at the point in question with the → celestial sphere.

→ geodetic; → zenith.