Diameter: 49,528 km
Mass: 17 Earths
Composition: Ice: Water & ammonia
Atmosphere: Hydrogen & helium
Surface Temperature: -201 °C
Year length: 165 Earth years
Day length: 16 hours
- Neptune is one of the four “gas giants” but is also regarded as one of two “ice giants” along with Uranus.
- Neptune orbits at a distance 30 times that of the Earth from the Sun.
- With winds as high as 2100 kmph, Neptune has the strongest winds in the Solar System.
- Neptune was originally found by a mathematical prediction. Astronomers found changes in Uranus’ orbit which could only be explained by an unidentified planet.
- Subsequently, Neptune was then finally observed in 1846 by Johann Galle.
- Neptune is named after the Roman god of the sea.
- Voyager 2 conducted the first flyby in 1989, observing the “great dark spot”, similar to that of the larger gas giant, Jupiter’s, “great red spot”.