Space and Time
Size: Diameter 51,118km
Mass: 8.683x10(exp25)kg
Composition: Rock, ice
Mean temperature: -214°c
Distance from Sun: 2875 million km
Atmosphere/weather: Hydrogen, helium and methane
Moon/satellites: At least 20
Orbital length: 30, 685.9 days
Length of day: 17 hours 12 minutes
Distance from Earth: Max 3025 million km, min 2725 million km
Uranus is the seventh planet from the Sun and the third largest, by diameter. Uranus was discovered in 1781 by astronomer William Herschel. At first he thought it was a comet. It is so distant that it takes 84 years to complete an orbit.
Once considered one of the less interesting-looking planets, Uranus has been revealed as a dynamic world with some of the brightest clouds in the outer solar system and eleven rings. Uranus gets its blue-green colour from methane gas above the deeper cloud layers (methane absorbs red light and reflects blue light).
Uranus is classified as a 'gas giant' because it has no solid surface. The atmosphere of Uranus is hydrogen and helium, with a small amount of methane and traces of water and ammonia. The bulk (80 percent or more) of the mass of Uranus is contained in an extended liquid core consisting primarily of 'icy' materials (water, methane, and ammonia), with higher-density material at depth.
This false-colour image of Uranus clearly shows its tilt and its rings
A collision with an Earth-sized object millions of years ago may be the reason that Uranus is tipped on its side. Its south pole points directly at the Sun.
Uranus' rings were first discovered in 1977. The rings are in the planet's equatorial plane, perpendicular to its orbit about the Sun. The ten outer rings are dark, thin and narrow, while the eleventh ring is inside the other ten and is broad and diffuse. The rings of Uranus are very different from those surrounding Jupiter and Saturn. When viewed with the Sun behind the rings, fine dust can be seen scattered throughout all of the rings.
Uranus has at least 20 moons, named mostly for characters from the works of Shakespeare and Alexander Pope. Miranda is the strangest Uranian moon. The high cliffs and winding valleys of the moon may indicate partial melting of the interior, with icy material occasionally drifting to the surface.
Uranus is the ancient Greek deity of the heavens, the earliest supreme god. Uranus was the son and mate of Gaia, the father of Cronus (Saturn) and of the Cyclopes and Titans (predecessors of the Olympian gods).
Images, information and videos courtesy of NASA.