Umbriel
Uranus II
Umbriel Facts
- Umbriel is the thirteenth of Uranus's known
satellites and the third largest:
- distance from Uranus: 265,980 km
- diameter: 1170 km
- mass: 1.27e21 kg
- Pronounced "UM bree el"
- 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's 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's
brightest satellite.
Pictures
- (above) Umbriel
28k gif;
8k jpg;
123k gif
Umbriel: color large low res
47k jpg
More about Umbriel
Open Issues
- Umbriel is significantly darker than the other large moons of Uranus. Why?
- What is the bright spot near the terminator?
... Uranus
... Ariel
... Umbriel
... Titania
... 
Bill Arnett; last updated:
1995 January 16