This is the most distant planet from the sun, within our solar system. It is 30 times further away from the sun than Earth.
Neptune is the smallest of the ice giants and the furthest away. This means it wasn't discovered until 1846, making it the first planet to be predicted by mathematics before being sighted.
Although smaller than neighbouring Uranus, it has a larger mass.
The atmosphere of Neptune is made up of hydrogen, helium and methane gases. Most of the planet's mass is made up of a hot dense fluid of water, methane and ammonia which surrounds a rocky core.
Neptune takes 16 hours to complete a rotation of its axis and 165 Earth years to complete a single journey around the sun.
The climate on Neptune is very active, with winds reaching up to 600 metres per second. One storm was recorded in 1989 and lasted for five years!
14 moons have been identified so far. The largest is Triton, unusual for the fact it is the only moon in the solar system that travels in the opposite direction to the planet's rotation.
Neptune has only been visited by one spacecraft.
This was a fly-by done by the Voyager 2 probe in 1989 as it navigated through the outer solar system.
It took Voyager 2 about ten years to reach Neptune, although its route did involve fly-bys of Jupiter, Saturn and Uranus first.
There are currently no confirmed upcoming missions to Neptune. Although the next suitable launch window is not until 2031.
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