Central meridian

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Central meridian of a celestial body through its north pole N S and the center M of the visible celestial body disc

The central meridian is the longitude of a celestial body that runs through its apparent center at a given point in time . The apparent center is the center of the disc of the celestial body that the observer sees at the specified time. The central meridian bound to the observer thus differs from a prime meridian which is defined independently of the observer by a reference point on the surface of the celestial body and rotates with the celestial body. The angle L 0 between the central and prime meridian thus changes in the course of the rotations of celestial bodies and earth.

The central meridian is listed for the sun and especially the planets Mars , Jupiter and Saturn in the astronomical yearbooks . Since Jupiter and Saturn rotate faster in their equatorial zone than in higher latitudes ( differential rotation ), different numerical values ​​are to be used for the areas near and far from the equator (system I and system II).

See also

Individual evidence

  1. ↑ Oliver Montenbruck: Basics of the ephemeris calculation . 7th edition. 2009, ISBN 978-3-8274-2292-7 , pp. 109 ( limited preview in Google Book search).