Oberon

Oberon

Oberon in Orbiter 2016 with D3D9 client, with Uranus in the background
Designation
Name	Oberon
Reference body	Uranus
Planetary mean orbits
Epoch	2010
Semimajor axis (a)	583390000 m
Eccentricity (e)	0.0021
Inclination (i)	97.88697451° (1.70845 radian)
Longitude of the ascending node (LAN, ☊)	167.7349988° (2.927528 radian)
Longitude of periapsis (ϖ)	8.846009991° (0.154392 radian)
Mean longitude (L)	261.319003° (4.560877 radian)
Selected physical parameters
Mean radius	7614 km
Mass	3.03×10²¹ kg
Note	*Elements given are from Oberon.cfg (2016)

Oberon is the second largest and second most massive natural satellite of Uranus. It was discovered on 11 January 1787 by William Herschel, and was named after a character from William Shakespeare's A Midsummer Night's Dream. It is one of the five satellites of Uranus discovered prior to the Voyager 2 encounter of January 1986.

Oberon has a radius of 761.4km. Its surface gravity is 0.349m/s^2, 0.036 that of Earth. A surface orbit has a speed of 515m/s, and the escape velocity is 729m/s. A surface orbit has a period of 9283s (about 2 hours 35 minutes).

Oberon's orbit about Uranus is almost perfectly circular and equatorial, and has a radius of 583400km. Its orbital period is 13.463 days. This is the outermost of the five major satellites.

Like all the satellites of Uranus, Oberon's axis is tilted 98° relative to the ecliptic plane. It is locked in synchronous rotation, like the Earth's moon. When Voyager flew past, Uranus and all its satellites were near their southern summer solstice, and in this case it means that only the southern hemispheres were visible. As a consequence, only the southern hemisphere of Oberon has been mapped in any detail.

Oberon has a mean density of about 1.6 times that of water. From this, we can conclude that the satellite is mostly water ice, with a little bit of rock mixed in.