Umbriel
Umbriel information Average distance from Uranus: 265998 km (0.0018 AU) Equatorial radius: 584.7 km (Diameter: 1169.4 km) Mass: 1170000000000000000000 kg Siderial orbit period (length of year): 4.1441772 earth days Orbital eccentricity: 0.0050 Orbital inclination to ecliptic: 0.36 degrees		Umbriel, Uranus II
Umbriel Umbriel is a character in Alexander Pope's The Rape of the Lock. Discovered by Lassell in 1851. Umbriel and Oberon appear quite similar though Oberon is 35% larger. All of Uranus' large moons are a mixture of about 40-50% water ice with the rest rock, a somewhat larger fraction of rock than Saturn's large moons such as Rhea. Umbriel's heavily cratered surface has probably been stable since its formation. It has far more and larger craters than do Ariel and Titania. Umbriel is very dark; it reflects only about half as much light as Ariel, Uranus' brightest satellite.
More Discovered by W. Lassell in 1851
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