Neptune

Neptune is best around opposition, when Earth passes between it and the Sun. Then it rises around sunset, is up all night and is at its brightest.

Neptune was at opposition on September 26, 2026, so it is still well placed in the evening sky. The next opposition is on September 28, 2027.

Neptune is the eighth and most distant planet from the Sun, an ice giant a little smaller than Uranus. It was the first planet found by mathematics: in 1846 astronomers predicted its position from the way it tugged on Uranus, and it was spotted within a degree of that spot.

Its deep blue color comes from methane gas in the atmosphere. Neptune has the fastest winds measured on any planet, more than 2,000 km/h, and dark storms that come and go.

One year on Neptune lasts about 165 Earth years, so it has completed only one orbit since its discovery. Its largest moon, Triton, orbits backwards and is probably a captured object from the Kuiper Belt.

Voyager 2 is the only spacecraft to have visited Neptune, in 1989.

Neptune gives off more than twice as much heat as it receives from the Sun, which helps power its weather. It has a faint system of dark, dusty rings, one of which contains unusual bright clumps called arcs. Most of its moons are named after sea gods and nymphs from Greek mythology.