Planetary Orbits & Ephemerides
Horizons
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.
Note that information on Pluto may be found on the
Planetary Satellites/Orbits
page, and that information for known Kuiper Belt Objects (KBOs),
such as 486958 Arrokoth (the object investigated by the New Horizons mission,
and originally and informally called “Ultima Thule”) may be found by specifying
the minor planet designation (which for Arrokoth is 486958) in the
Horizons
system.
Lower accuracy formulae for planetary positions
have a number of important applications
when one doesn’t need the full accuracy of an integrated ephemeris.
Using these formulae with Keplerian elements for the planets provide suitable positions
for such applications.
Details for using this method are provided on the
Approximate Positions of the Planets
page.
Ephemerides
The JPL planetary and lunar ephemerides Development Ephemeris (DE) series
includes the positions of the Sun, the barycenters of eight planetary systems, the Moon,
the Pluto system barycenter, and lunar libration angles, as well as their associated velocities.
Ephemerides are generally created to support spacecraft missions to the planets.
New ephemerides are generated periodically to include new data and refine the dynamical models.
The
JPL planetary and lunar ephemerides export information
file contains a
detailed description of the different ephemeris versions available as well as the links from
which the ephemeris files can be downloaded.
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?website
.