(outer-most solar system planet)
Neptune is the outer-most known planet in the solar system.
- 30 AU - orbital radius.
- 17 Earth masses.
- 3.85 Earth radii.
Among the solar system planets,
it is easily most similar to Uranus,
with a slightly larger mass and a slightly smaller radius.
Neptune has 14 moons, of which one, Triton, is substantial.
Triton has a retrograde orbit, suggesting it is a captured minor planet.
Pluto and Neptune have a 3:2 orbital resonance.
The only mission to fly near Neptune was Voyager 2 in 1989.
The term Neptune is also used for Neptune-like
extra-solar planets, specifically significantly larger than
Earth and smaller than Jupiter or Saturn,
and typically a gas planet, perhaps with other
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astronomical unit (AU)
equilibrium temperature (Teq)
Kuiper Belt (K Belt)
late heavy bombardment (LHB)
moment of inertia factor
solar mass (MSun)
Outer Solar System Origins Survey (OSSOS)
trans-Neptunian object (TNO)