Umbriel

Umbriel is the third-largest <a href="/facts/Moon_of_Uranus/evfGRq7F">moon of Uranus</a>. It was discovered on October 24, 1851, by <a href="/facts/William_Lassell/JoEW3Ird">William Lassell</a> at the same time as neighboring moon <a href="/facts/Ariel_(moon)/v7arpRGo">Ariel</a>. It was named after a character in <a href="/facts/Alexander_Pope/Tj8QDdeV">Alexander Pope</a>'s 1712 poem <a href="/facts/The_Rape_of_the_Lock/k4wHVvdI">The Rape of the Lock</a>. Umbriel consists mainly of <a href="/facts/Ice/BGvkKFjD">ice</a> with a substantial fraction of <a href="/facts/Rock_(geology)/FXCJkmop">rock</a>, and may be <a href="/facts/Planetary_differentiation/fvjC1107">differentiated</a> into a rocky <a href="/facts/Core_(geology)/LyQ7DbAl">core</a> and an icy <a href="/facts/Mantle_(geology)/RpDdtjCr">mantle</a>. The surface is the darkest among Uranian moons, and appears to have been shaped primarily by impacts, but the presence of canyons suggests early internal processes, and the moon may have undergone an early endogenically driven resurfacing event that obliterated its older surface.
Covered by numerous <a href="/facts/Impact_crater/nWntooh4">impact craters</a> reaching 210 km (130 mi) in diameter, Umbriel is the second-most heavily cratered satellite of Uranus after <a href="/facts/Oberon_(moon)/Xmfrr6aK">Oberon</a>. The most prominent surface feature is a ring of bright material on the floor of <a href="/facts/Wunda_(crater)/AW0NBdwU">Wunda</a> crater. This moon, like all regular moons of Uranus, probably formed from an <a href="/facts/Accretion_disk/8zJXshat">accretion disk</a> that surrounded the planet just after its formation. Umbriel has been studied up close only once, by the spacecraft <a href="/facts/Voyager_2/9FAEaHUr">Voyager 2</a> in January 1986. It took several images of Umbriel, which allowed mapping of about 40% of the moon's surface.

Umbriel open-in-new

Umbriel