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Pictured as a featureless disc by Voyager 2 in 1986

Uranus (from the Latin name Ūranus for the Greek god Οὐρανός) is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both have bulk chemical compositions which differ from that of the larger gas giants Jupiter and Saturn. For this reason, scientists often classify Uranus and Neptune as "ice giants" to distinguish them from the gas giants. Uranus' atmosphere is similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, but it contains more "ices" such as water, ammonia, and methane, along with traces of other hydrocarbons. It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224 °C; −371 °F), and has a complex, layered cloud structure with water thought to make up the lowest clouds and methane the uppermost layer of clouds. The interior of Uranus is mainly composed of ices and rock.

Like the other giant planets, Uranus has a ring system, a magnetosphere, and numerous moons. The Uranian system has a unique configuration 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).

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.

Selected article

Location of Desdemona
Desdemona (/ˌdɛzdɪˈmnə/ DEZ-di-MOH-nə) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 13 January 1986, and was given the temporary designation S/1986 U 6. Desdemona belongs to Portia Group of satellites, which also includes Bianca, Cressida, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita. Desdemona may collide with one of its neighboring moons Cressida or Juliet within the next 100 million years.

Selected biography

William Lassell
Born in Bolton, he made his fortune as a beer brewer, which enabled him to indulge his interest in astronomy. He built an observatory near Liverpool with a 24-inch (610 mm) reflector telescope. In 1846 Lassell discovered Triton, the largest moon of Neptune, just 17 days after the discovery of Neptune itself by German astronomer Johann Gottfried Galle. In 1848 he independently co-discovered Hyperion, a moon of Saturn. In 1851 he discovered Ariel and Umbriel, two new moons of Uranus.


Uranus Atmosphere ˑ Climate ˑ Exploration (Voyager 2) ˑ Rings

Moons (Portia ˑ Puck ˑ Miranda ˑ Ariel ˑ Umbriel ˑ Titania ˑ Oberon ˑ Caliban ˑ Sycorax)

Astronomers: William Herschel ˑ William Lassell ˑ Gerard Kuiper ˑ James L. Elliot

See Also: Formation and evolution of the Solar System ˑ Gas Giant ˑ Nebular hypothesis

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Italicized articles are on dwarf planets or major moons.


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