|Diameter||51000 km, 4 x Earth's|
|Mean Density||1.3 g/cm3|
|Mean Distance from Sun||2870 x 106km = 19.2 AU|
|Eccentricity of Orbit||0.047|
|Inclination of Equator to Orbit||98°|
|Inclination of Orbit to Ecliptic||0.8°|
Traces of ethene
|Length of Day||17.3 hours|
|Length of Year||84 years|
|No. of Moons||15|
|Gravity||1.15 x Earth's|
|Escape Velocity||21.1 km/s|
Uranus is the seventh planet from the Sun, and the third of the gas giants. It is the first planet to have been discovered recently, first spotted by William Herschel in 1781. It has fifteen moons, all of which are named after characters from the writings of Shakespeare and Pope.
Miranda is one of the more interesting moons. Its surface features and composition are very discontinuous, as if parts of the moon on the outside should really be on the inside. It is now believed that Miranda formed in the same way as the other moons, with a very normal surface and cross-section, but that the moon was hit by something so large that it was completely shattered. These chunks of rock would then have reformed under the influence of gravity, but would have done so in a different order so some areas that were previously on the inside of the moon would have been added to the outside and vice-versa. This would explain the discontinuous structure seen today.
Uranus also has a faint ring system like Saturnís but this is made from darker rocks so it is harder to see.
Uranus, like all the planets, is seen by reflected light. However, all of the red light shining onto it is absorbed by the methane in its atmosphere, making the planet look blue.
Scientists argue about which way Uranus is spinning. Either the north pole points slightly down and the planet is spinning the same way as most of the others (in the prograde direction) or the north pole points slightly up and the planet spins the same way as Venus (retrograde).
Authors: Carolyn Brinkworth and Claire Thomas
Last updated: July 2001