Oberon

Oberon or Uranus IV is the eighteenth moon of Uranus, and the outermost of the major moons of Uranus. It is also the second largest moon of Uranus.

Discovery and naming
William Herschel discovered Oberon and its inner companion, Titania, on January 11, 1787.

Sir John Herschel, his son, gave to Oberon the name of the king of the fairies in William Shakespeare's comedy, A Midsummer Night's Dream.

Orbital characteristics
Oberon is in a slightly eccentric orbit around Uranus, at an average distance of 583,520 km. Its sidereal month is about 13.46 Earth days.

Rotational characteristics
Oberon is in tidal lock with Uranus.

Physical characteristics
Oberon is the second largest of the moons of Uranus. It is probably composed of water ice and rock.

Surface
The surface of Oberon has many impact craters. Many of these have bright rays that radiate from them, similar to those found on Callisto.

The surface, including many of the crater floors, is partially covered with a dark material of unknown origin. Some astronomers speculate that this material is an aqueous solution that upwelled from the interior.

Problems for uniformitarian theories posed by Oberon
Oberon poses the same problem for uniformitarian astronomy as do all the other moons of Uranus: its orbit is inclined severely to the ecliptic, though not to Uranus' own equator. How the Uranian system came to have such an inclination has never been explained.

Observation and Exploration
Oberon is visible on a dark sky through a telescope having an aperture of 30 cm or more.

The only spacecraft to explore Oberon has been Visiting mission::Voyager 2. It approached to within 470,600 km of Oberon on January 24, 1986, and took a small number of images. No other detailed images are available.

Related Links

 * Oberon by Wikipedia

Obéron