Uranus is the only planet whose name is derived directly from a figure from Greek mythology, from the Latinised version of the Greek god of the sky Ouranos. Like the other giant planets, Uranus has a ring system, a magnetosphere, and numerous moons. The Uranian system has a unique configuration among those of the planets because its axis of rotation is tilted sideways, nearly into the plane of its solar orbit. Its north and south poles, therefore, lie where most other planets have their equators. In 1986, images from Voyager 2 showed Uranus as an almost featureless planet in visible light, without the cloud bands or storms associated with the other giant planets. Observations from Earth have shown seasonal change and increased weather activity as Uranus approached its equinox in 2007. Wind speeds can reach 250 metres per second (900 km/h; 560 mph).

Like the classical planets, Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel announced its discovery on 13 March 1781, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet discovered with a telescope.

Inside Uranus

The Core

Uranus is a frozen, gaseous planet.

Atmosphere: The planet is shrouded in an icy cloud layer (made up of frozen methane, ethane, and acetylene) circling this planet at 185 mph (300 kph. Uranus' icy atmosphere consist of 83% hydrogen,15% helium, and 2% methane. The outer layers of the atmosphere are the coldest; temperature and pressure rise under the cloud layer.

Partially-solid Layers: Beneath the atmosphere, there is a liquid layer of hydrogen and helium. As depth increases, this layer becomes more viscous, and then partly solid. This layer may be composed of compressed water with ammonia and methane.

Core: Uranus has a molten rocky core about 10,500 miles (17,000 km) in diameter and about 12,500°F (6927°C). This core may have a mass five times greater than the mass of the Earth.

Uranus Facts