Oberon (moon)
Moon of Uranus / From Wikipedia, the free encyclopedia
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Oberon /ˈoʊbərɒn/, also designated Uranus IV, is the outermost and second-largest major moon of the planet Uranus. It is the second-most massive of the Uranian moons, and the tenth-most massive moon in the Solar System. 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. Its orbit lies partially outside Uranus's magnetosphere.
Discovery | |
---|---|
Discovered by | William Herschel |
Discovery date | January 11, 1787[1] |
Designations | |
Designation | Uranus IV |
Pronunciation | /ˈoʊbərɒn/ or /ˈoʊbərən/[2] |
Adjectives | Oberonian /ɒbəˈroʊniən/[3] |
Orbital characteristics | |
583520 km[4] | |
Eccentricity | 0.0014[4] |
13.463234 d[4] | |
Average orbital speed | 3.15 km/s (calculated) |
Inclination | 0.058° (to Uranus's equator)[4] |
Satellite of | Uranus |
Physical characteristics | |
Mean radius | 761.4±2.6 km (0.1194 Earths)[5] |
7285000 km2[lower-alpha 1] | |
Volume | 1849000000 km3[lower-alpha 2] |
Mass | (3.1104±0.0749)×1021 kg[7] |
Mean density | 1.682 g/cm3 (calculated) |
0.358 m/s²[lower-alpha 3] | |
0.738 km/s[lower-alpha 4] | |
presumed synchronous[8] | |
Albedo |
|
Temperature | 70–80 K[10] |
14.1[11] | |
Oberon likely formed from the accretion disk that surrounded Uranus just after the planet's formation. 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. 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 chasmata (graben or scarps) formed during crustal extension as a result of the expansion of its interior during its early evolution.
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.