Neptune is the eighth planet in distance from the Sun and the farthest in the Solar System. It is part of the so-called outer planets or gas giants, and is the first to be discovered thanks to mathematical predictions. It was discovered by Johann Galle in 1846, following the calculations of Urbain Le Verrier. Its name refers to the Roman god of the sea. Neptune is the fourth planet in diameter and the third largest in mass. Its mass is 17 times that of Earth and slightly larger than that of its "twin" planet Uranus, which has 15 land masses and is not as dense. On average, Neptune orbits the Sun at a distance of 30.1 astronomical units. Neptune is a dynamic planet, with spots reminiscent of Jupiter's storms. The largest, the Great Dark Spot, was about the same size as Earth, but in 1994 it disappeared and another has formed. It has the strongest winds of any planet in the Solar System.
