- Distance
- 30.1 AU
- Diameter
- 49,244 km
- Year
- 165 years
- Day
- 16 h 6 m
- Moons
- 16
About Neptune
Neptune was found in 1846 exactly where calculations based on irregularities in Uranus's orbit predicted it would be. It is a near-twin of Uranus in size and composition but far more active, with winds reaching 2,100 km/h and dark storms that come and go. Its largest moon, Triton, orbits backwards and is probably a captured Kuiper belt object; it has nitrogen geysers and a surface at −235 °C. Neptune has five faint rings and 16 known moons. Since its discovery it has completed only one full orbit, in 2011. Voyager 2 flew past in 1989.
- Fastest winds recorded on any planet
- Sunlight takes over 4 hours to arrive
- Triton is one of the coldest known objects in the Solar System
Moons
| Name | Diameter | Notes | |
|---|---|---|---|
 | Triton | 2,707 km | Neptune's giant moon orbits backwards, a sign it was captured from the Kuiper belt. Voyager 2 saw geysers of nitrogen erupting from its frozen surface at −235 °C. |
| Proteus | 420 km | An irregular, dark moon discovered by Voyager 2, as large as a body can be without gravity pulling it into a sphere. | |
| Nereid | 340 km | A moon on a wildly elongated orbit that carries it between 1.4 and 9.7 million km from Neptune. |
In pictures