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Uranus is the seventh planet from the Sun and is the third largest in the solar system. It was discovered by William Herschel in 1781. It has an equatorial diameter of 51,800 kilometers (32,190 miles) and orbits the Sun once every 84.01 Earth years. It has a mean distance from the Sun of 2.87 billion kilometers (1.78 billion miles). The length of a day on Uranus is 17 hours 14 minutes. Uranus has at least 15 moons. The two largest moons, Titania and Oberon, were discovered by William Herschel in 1787. The atmosphere of Uranus is composed of 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and other hydrocarbons. Methane in the upper atmosphere absorbs red light, giving Uranus its blue-green color. Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the solar system's history. |
