Known Space -- Sol -- Uranus -- | Umbriel |
Umbriel is the thirteenth of Uranus's satellites and the third largest. 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.
Orbital Distance: 264,650 km - 267,310 km (average 265,980 km) Eccentricity: 0.005 Local Year: 4.144 days (4d 3h 27m 37s) Orbital Velocity: 4.668 km/s Inclination: 0.36° Local Day: 4.144 days (4d 3h 27m 37s) Axial Tilt: n/a Diameter: 1,170 km Composition: H2O ice and rock Density: 1.51 g/cm3 Mass: 1.27 x 1018 tonnes (0.0002 earths) Gravity: 0.025 G Escape Velocity: 0.538 km/s Area: 4.3 million km2 Surface Material: H2O ice and rock Atmosphere: None Pressure: None Albedo: 0.18 Temperature: ???°C |