Portal:Uranus

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Uranus

A photo of Uranus taken by Voyager 2.

Uranus is the seventh planet from the Sun; it is the third largest and fourth most massive planet in the solar system. Uranus was the first planet discovered in modern times. Though it is visible to the naked eye like the five classical planets, it was never recognised as a planet by ancient observers due to its dimness. Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the solar system. Uranus' atmosphere, although similar to Jupiter and Saturn in being composed primarily of hydrogen and helium, contains a higher proportion of "ices" such as water, ammonia and methane, along with the usual traces of hydrocarbons. It has the coldest planetary atmosphere in the solar system, with a minimum temperature of 49 K, and has a complex layered cloud structure in which water is thought to make up the lowest clouds, while methane makes up the uppermost layer of clouds. In 1986, images from the Voyager 2 space probe showed Uranus as a virtually featureless planet in visible light without the cloud bands or storms associated with the other giants. The wind speeds on Uranus can reach 250 m/s (560 mph).

More about...Uranus: its history, rings, atmosphere, climate, moons, and its exploration


Selected article

Umbriel as seen by Voyager 2 in 1986
Umbriel /ˈʌmbriəl/ is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle. The surface is the darkest among Uranian moons, and appears to have been shaped primarily by impacts. However, the presence of canyons suggests early endogenic processes. Covered by numerous impact craters reaching in diameter 210 km, Umbriel is the second most heavily cratered satellite of Uranus after Oberon. The most prominent surface feature is a ring of bright material on the floor of Wunda crater. This moon, like all moons of Uranus, probably formed from an accretion disk that surrounded the planet just after its formation.

Selected biography

Gerard Kuiper
Gerard Peter Kuiper (/ˈkpər/; Dutch pronunciation: [ˈkœypər]; born Gerrit Pieter Kuiper December 7, 1905, Harenkarspel (Tuitjenhorn), Netherlands – December 24, 1973, Mexico City) was a Dutch astronomer who became a naturalized citizen of the United States. Kuiper discovered two natural satellites of planets in the solar system, namely Uranus's satellite Miranda and Neptune's satellite Nereid. In addition, he discovered carbon dioxide in the atmosphere of Mars and the existence of a methane-laced atmosphere above Saturn's satellite Titan in 1944.

Topics

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

Bold articles are featured.
Italicized articles are on dwarf planets or major moons.


Selected picture

Canyons on Ariel
Credit: NASA/JPL

This highest-resolution Voyager 2 view of Ariel's terminator shows a complex array of transecting valleys with super-imposed impact craters. Voyager obtained this clear-filter, narrow-angle view from a distance of 130,000 kilometers (80,000 miles) and with a resolution of about 2.4 km (1.5 mi). Particularly striking to Voyager scientists is the fact that the faults that bound the linear valleys are not visible where they transect one another across the valleys. Apparently these valleys were filled with deposits sometime after they were formed by tectonic processes, leaving them flat and smooth. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

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