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Refers to a reference system centered at the Earth's center. A major difference between geocentric and topocentric ephemerides is that no local horizon exists (and therefore derived quantities such as azimuth and elevation are not defined) for a geocentric ephemeris.
The list of defined terms to the left is by no means exhaustive with
respect to the general subject of solar system dynamics.
The terms listed are thought to be those more commonly used on our site
and thus appropriate for inclusion on this page.