Naiad, a moon of Neptune
Naiad from Voyager 2 in 1989. The moon appears stretched due to its movement while image was being taken, image credit: NASA
29,998 miles
38 miles
Naiad is a small moon of Neptune. It is one of Neptune's inner moons and is the closest moon to orbit the planet. Naiad has a diameter of approximately 60 kilometres (38 miles). It orbits Neptune at a distance of just over 48,000 kilometres (30,000 miles). A length of an orbit takes only 7 hours which means that it orbits Neptune faster than the planet spins.
Naiad is believed to be the fragments of an earlier moon that was destroyed when Neptune captured its largest moon Triton. Parts of that destroyed moon joined back together to form Naiad and several of Neptune's other inner moons.
It is thought that Naiad itself will be destroyed at some point in its very distant future. Its orbit is likely to decay which will bring it closer and closer to Neptune until it either falls into Neptune's atmosphere or gets torn apart by gravitational forces. It will possibly form a ring.
Naiad is classed as a regular prograde moon. Regular moons are moons that formed out of materials spinning around a planet. Irregular moons are ones that were captured by a planet. A prograde moon is one which orbits in the same direction of the rotation of its host planet.