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Planetary Satellites Orbits & Ephemerides


Planetary satellites ephemerides are available using JPL’s Horizons system. The Horizons service offers comprehensive access to the positions and other information on solar system objects, including the Sun, planets, planetary barycenters, planetary satellites, asteroids, comets, Lagrange Points, selected spacecraft, in a variety of forms and formats. It is the suggested means of obtaining such information for a wide range of analyses.

Mean Elements

Mean orbital elements approximately represent the elliptical orbits of planetary satellites. They are computed by fitting numerically integrated data using a least-squares procedure. Because of their limited precision, mean orbital elements should not be used for high-fidelity applications.


High precision ephemerides files for selected planetary satellites are available for download from the planetary satellite ephemerides page. The use of these ephemeris files is recommended only for professionals whose needs are not readily met by the Horizons system. Alternatively, you may use the NAIF SPICE toolkit and planetary satellite ephemerides in SPK format from JPL’s NAIF website.