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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

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Diagram representing orbits of Uranus' irregular satellites
Sycorax (/ˈsɪkəræks/ SIK-or-aks) is the largest retrograde irregular satellite of Uranus. Its diameter is about 150 km. Sycorax was discovered on 1997-09-06 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale telescope, together with Caliban and given the temporary designation S/1997 U 2. In the visible light this satellite is red in color.

Selected biography

William Herschel
Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel, (15 November 1738 – 25 August 1822) was a German-born English astronomer, technical expert and composer who became famous for discovering Uranus and its two satellites. He also discovered infrared radiation, devised the first model of the Milky Way galaxy and made many other discoveries in astronomy.


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.

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To-scale schematic of the ring and moon system of the planet Uranus
Credit: User:Ruslik0

The scheme shows all rings (solid lines) and inner moons (dashed lines) of Uranus.

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A planet, Uranus, as seen by Voyager 2

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