True-color image of Uranus made by Voyager 2 in January 1986, combined with a 1998 Hubble Space Telescope infrared image of the planet's dark rings.

Orbital Elements
Mean distance from Sun2,870,990,000 km    =    19.1914 astronomical units
Perihelion distance2,741,300,000 km=    18.3245 astronomical units
Aphelion distance3,003,620,000 km=    20.078 astronomical units
Eccentricity of orbit0.0461
Inclination of orbit0.774relative to Earth's orbit
Period of orbit84.01 years
Synodic period370 daysrelative to Earth
Mean orbital speed6.81 km/s
Minimum orbital speed6.49 km/s
Maximum orbital speed7.11 km/s
Physical Properties
Mean diameter50,724 km=    4  Earth diameters
Equatorial radius25,559 km
Mass8.686 x 1025 kg=    14.535 Earth masses
Mean density1.29 g/cm3
Rotational period17.9 hours
Inclination of axis97.86relative to the axis of its orbit
Gravity at cloud tops7.77 m/s2
Escape speed21.3 km/sfrom cloud tops
Visual geometric albedo0.51
Visual magnitude (Vo)5.52maximum, as seen from Earth
Mean visible cloud temperature    -193C
Atmospheric pressure1.2 barsat cloud tops

Atmospheric Composition
Hydrogen (H2)83%
Helium (He)15%
Methane (CH4)  2%


Five medium-size moons and more than 20 small moons.

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Jeff Root
October 12, 2003