- Additional Information
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Additional Information
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 0° Albedo Bond 0.10 Albedo geometric 0.26 Temperature mean 02 75 K Temperature max 02 85 K Apparent magnitude 14.5 - Comments
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