(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)
Transiting Exoplanet Survey Satellite (TESS)
trans-Neptunian object (TNO)