Space Book

Uranus

UranusUranus is the 7th planet from the Sun with an average distance of 5 AU or 2.871 x 109 km. It takes 84.099 Earth years to orbit the Sun, and rotates at a rate of 1 rotation every 17.24 hours. It is the third largest planet in the Solar System with a mass of 8.682 x 1025 kg or 14.53 Earth masses. It has 27 confirmed moons, and the five main ones are Miranda, Ariel, Umbriel, Titania and Oberon. The average temperature of Uranus at the cloudtops is about 55 K (−218 °C or −360 °F).

Uranus can occasionally be seen with the naked eye from very dark sites, and was first discovered in 1781. Uranus has a very complex ring system with at least 13 rings. The rings are relatively thin, and are believed to be the result of a moon or moons being shattered by some kind of impact. Uranus has an unusual magnetic field, which is oriented at a 59° angle to its axis of rotation.

Uranus was visited by Voyager 2 in 1986.

Uranus Factbox
 Average distance from Sun  19.194 AU = 2.871 x 109 km = 717,750 widths of Australia
 Number of moons  27
 Average orbital speed  6.83 km/s
 Orbital period  84.099 years
 Rotation period  17.24 hours
 Inclination of equator to orbit  97.86°
 Diameter  51,118 km = 4.007 Earth diameters
 Mass  8.682 x 1025 kg = 14.53 Earth masses
 Average density  1318 kg/m3
 Surface gravity (Earth = 1)  0.9
 Albedo 0.56
 Average temperature at cloudtops -218°C = -360°F = 55 K
 Atmosphere  82.5% hydrogen, 15.2% helium, 2.3% methane