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Distance from sun 2,870.99 million km, 19.1914 a.u.
Diameter 51,118 km, 3.98 times earth's diameter
Mass 14.531 times earth's mass
Density 1.29
Gravity 0.793 times earth's gravity, escape velocity 21.3 km/s
Rotation 17.9 hours
Orbit Eccentricity 0.0461
Orbit Inclination 0.774 degrees
Axis Tilt 97.86 degrees
Sidereal Period 84.01 Earth years
Synodic Period 369.66 Earth days

History: Uranus was the first planet to be discovered in modern times. It was found by a German astronomer, William Herschel, in 1781, who also found two of its satellites a few years later. Johann Bode suggested naming it after a mythological character, and Uranus was chosen. In Greek mythology, Uranus was the primordial sky god, long before the Olympian gods arose. The titan Saturn was one of his sons.

Description: Uranus is one of three planets to rotate backwards compared to the others. Also, Uranus's axis is tilted98 degrees, placing it near its plane of orbit rather than perpendicular to it like most planets. Uranus is a gas giant about the size of Neptune, about four times the size of the earth. Despite its large mass, an object on the planet would only weigh 79 percent of what it weighs on earth, because of its low density. Like the other gas giants, its atmosphere consists mostly of hydrogen and helium, with other trace elements. Like Saturn, a thick, high altitude haze covers most of the cloud features below. Uranus has a series of faint rings, only visible from earth at times of an occulation.

Observation: Uranus is very dim, never exceeding sixth magnitude. It is only visible to the naked eye under perfect conditions and only appears as a dim star. In a small telescope it can be seen as a small greenish disk, but no details can be seen. Because of a siderial period of about 84 years, it stays in the same constellation for almost a decade.

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