+ View the NASA Portal
+ Center for Near-Earth Object Studies IMPORTANT: The SSD Announcement email list is now available. Major changes are coming in the near future, including possible hostname and/or URL changes. To be notified of such changes, subscribe to this email list.
Please visit this page for more details.
Quick Links HORIZONS Planets Planetary Satellites Comets & Asteroids Spacecraft Ephemerides
High precision ephemerides for solar-system bodies are available on-line using JPL's HORIZONS system. Most optical and radar observers will be best served by using our HORIZONS system to generate custom observer-table ephemerides. Our on-line HORIZONS system can also be used to output ephemerides in the form of osculating orbital elements and/or Cartesian vectors (position, velocity, and acceleration). However, there are some ephemeris data files available for export (see below) for those rare cases when HORIZONS will not suffice.
Professionals requiring high-precision ephemerides readable from their own software may find ephemeris data files (in SPK format) and a software toolkit needed to read those files from JPL's NAIF web-site. SPK files for planetary and planetary satellite ephemerides are available from NAIF. Comet and asteroid SPK files may be generated using our HORIZONS system.
Planetary ephemerides are available using JPL's HORIZONS system. Although the HORIZONS system will be sufficient for the vast majority of ephemeris requests, JPL planetary and lunar ephemeris files (e.g. DE406) are also available. 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 ephemerides in SPK format from JPL's NAIF web-site.
Summary of available planetary ephemerides:
- HORIZONS (preferred solution)
- JPL ephemeris files (e.g. DE-0406)
- SPK format ephemeris files (e.g. DE-0406)
- formulae for approximate positions
Ephemerides for planetary satellites are available from JPL's HORIZONS system. Although mean orbital elements are also available for planetary satellites, you are strongly discouraged from using them to generate your own ephemerides, as they will be highly inaccurate for many bodies. The list of planetary satellite ephemerides available via HORIZONS is available in this table.
Comets & Asteroids
The Solar System Dynamics Group does not create spacecraft ephemerides. However, JPL's HORIZONS system can access trajectory solutions provided by the navigation teams of many missions and derive many ephemeris quantities related to position and velocity.2020-Jun-04 18:22 UT
(server date/time) Site Manager: Ryan S. Park Webmaster: Alan B. Chamberlin