Uranus and Neptune

Uranus

The seventh planet from the sun is much like its gaseous neighbors, with a cloudy surface, rapid winds, and a small rocky core.

Uranus: personification of heaven in ancient myth

Perhaps because of a collision with a large object long ago, Uranus orbits at an extreme tilt of 98 degrees -- sort of on its side. This causes one pole to point toward the sun for decades, giving the planet strange seasons.

Uranus has numerous satellites and a faint set of rings. If all the possible satellites being studied are confirmed, Uranus would have 16 regular and five irregular moons, making it the most populated planetary satellite system known. Saturn is known to have 18 satellites (there may be more, but they have not been well-documented).

Historical notes

Uranus was thought to be a star until William Herschel discovered in 1781 that it orbited the Sun.

Neptune

The eighth planet from the Sun -- well, some of the time it's eighth, but more on that later -- has a rocky core surrounded by ice, hydrogen, helium and methane.Like the other gas planets, Neptune has rapidly swirling winds, but it is thought to contain a deep ocean of water. Its quick rotation fuels fierce winds and myriad storm systems. The planet has a faint set of rings and 8 known moons.

Because of Pluto's strange orbit, Neptune is sometimes the most distant planet from the Sun. Since 1979, Neptune was the ninth planet from the Sun. On February 11, 1999, it crossed Pluto's path and once again become the eighth planet from the Sun, where will remain for 228 years.

Neptune: roman god of water

Historical notes

Neptune was discovered in 1846 after mathematical calculations of Uranus' movements predicted the existence of another large body.