Oberon is the outermost major
moon of the planet
Uranus. It is the second largest and second most massive of Uranian moons, and the ninth most massive moon in the Solar System. Discovered by
William Herschel in 1787, Oberon is named after a character in Shakespeare's
A Midsummer Night's Dream. Its orbit lies partially outside Uranus's
magnetosphere. Oberon consists of approximately equal amounts of ice and
rock, and is likely differentiated into a rocky
core and an icy
mantle. A layer of liquid water may be present at the core/mantle boundary. The surface of Oberon, which is dark and slightly red in color, appears to have been primarily shaped by asteroid and comet impacts. It is covered by numerous
impact craters reaching 210 km in diameter. Oberon possesses a system of
canyons (
scarps) formed as a result of the expansion of its interior during its early evolution. This moon probably formed from the
accretion disk that surrounded Uranus just after the planet's formation. As of 2010, the Uranian system has been studied up close only once: by the spacecraft
Voyager 2 in January 1986. It took several images of Oberon, which allowed mapping of about 40% of the moon’s surface.
