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In 2006, subsequent to several discoveries of several large outer Solar System objects beyond Pluto (one of which was found to be even larger than Pluto) it was decided that a planet should be defined as an object which (a) orbits the sun, and (b) is massive enough not only to coalesce itself into a nearly spherical shape, but also to gravitationally dominate its region of the solar system. Using this new definition, there are eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was re-classified as a “minor planet”. Nevertheless, for historical reasons, Pluto is still found with the 8 planets on the JPL Planetary Ephemeris.

See the complete Solar System planetary classification discussion.

Description of Menu Items

Orbits & EphemeridesProvides access to orbital data for all planets.
Physical ParametersTable of selected physical parameters for the planets and dwarf planets.
Gravity FieldsVisualize and download the gravity fields of several planets, the moon, and a few small-bodies.
Observational DataProvides sets of observations that are currently being used in the creation and improvement of modern planetary and lunar ephemerides.
Discovery CircumstancesDiscovery circumstances for the planets.