Oberon is the outermost major moon of the planet Uranus. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies who appears as a character in Shakespeare’s A Midsummer Night’s Dream. Oberon orbits Uranus at a distance of about 584,000 km, being the farthest from the planet among its five major moons.
About Oberon (moon) in brief
Oberon is the outermost major moon of the planet Uranus. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies who appears as a character in Shakespeare’s A Midsummer Night’s Dream. It is the second-largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Oberon orbits Uranus at a distance of about 584,000 km, being the farthest from the planet among its five major moons. The moon consists of approximately equal amounts of ice and rock, and is probably differentiated into a rocky core and an icy mantle. A layer of liquid water may be present at the boundary between the mantle and the core. Its orbit lies partially outside Uranus’s magnetosphere, and it is subject to an extreme seasonal cycle. Once every 42 years, when Uranus has an equinox and its equatorial plane intersects the Earth, mutual occultations become possible. One such event was observed on May 4, 2007, when Oberon occulted Umbriel, the second largest of the moons after Titania. The name Oberon was derived from Oberon, the King of the Fairies in A MIDSummer Night’s Dream. The adjectival form of the name is Oberonian, ˌɒb�’ˈroʊniən.
The Uranian system has been studied up close only once: the spacecraft Voyager 2 took several images of Oberon in January 1986, allowing 40% of the moon’s surface to be mapped. The Voyager 2 flyby coincided with the southern hemisphere’s solstice, when nearly the entire northern hemisphere was in darkness, when the sun rose close to the zenith over one of the summer solstice. The names of all four satellites of Uranus then known were suggested by Herschel’s son John in 1852, at the request of William Lassell, who had discovered the other two moons, Ariel and Umbriel the year before. In 1851 Lassell eventually numbered all four known satellites in order of their distance from the planets by Roman numerals, and since then Oberon has been designated Uranus IV. The northern and southern poles spend 42 years in a complete darkness, and another 42 years in continuous sunlight, with the sun rising close to one of them over each solstice at each summer. It has a density of 63g³, which is higher than the typical density of Saturn’s satellites, which indicates that it consists of roughly equal proportions of water and a non-non-water ice.