Umbriel

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Umbriel
Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle. The surface is the darkest among Uranian moons, and appears to have been shaped primarily by impacts. However, the presence of canyons suggests early endogenic processes, and the moon may have undergone an early endogenically driven resurfacing event that obliterated its older surface. Umbriel's surface is the darkest of the Uranian moons, and reflects less than half as much light as Ariel, a sister satellite of similar size. Umbriel (moon) - Wikipedia, the free encyclopedia
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Short Description Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle. The surface is the darkest among Uranian moons, and appears to have been shaped primarily by impacts. However, the presence of canyons suggests early endogenic processes, and the moon may have undergone an early endogenically driven resurfacing event that obliterated its older surface. Umbriel's surface is the darkest of the Uranian moons, and reflects less than half as much light as Ariel, a sister satellite of similar size. Umbriel (moon) - Wikipedia, the free encyclopedia
Discovered by William Lassell
Discovery date October 24, 1851
Type Moon
AddInfo Uranus II
Satellite of Uranus
Orbit Prograde
Rotation Synchronous
Shape Equilibrium spheroid
Geological activity In the past
Apoapsis 06 267 500 km
Periapsis 06 265 100 km
Semi-major axis 06 266 000 km
Distance from Sun 02 19.218 4 au /16
Eccentricity 0.003 9
Orbital period 4.144 days
Orbital speed  4.67 km/s
Inclination to the equator 000.128°
Diameter/Size 04 1169.4 km
Mass 1021×1.172 kg
Density 01 1.39 ± 0.16 g/cm3
Surface gravity  0.2 m/s2
Escape velocity 03 520 m/s
Rotation period 4.144 days
Axial tilt
Albedo Bond 0.10
Albedo geometric 0.26
Temperature mean 02 75 K
Temperature max 02 85 K
Apparent magnitude 14.5
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