Oberon
What is Oberon?
Moons· Diameter 1,523 km. The outermost and second-largest major moon of Uranus — ancient cratered terrain with an 11-km mountain and crater floors coated in mysterious dark material. See its slow outer orbit in the orbit view.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
The orbit of Oberon at this moment: https://nowsky.org/solar/orbit?fw=moon:uranus:oberon&sp=0.013 — replayed live, no login.
Orbit and size
| Diameter | 1,523 km |
|---|---|
| Distance from Uranus | 583,500 km |
| Orbit | 13.5 d |
| Note | 11-km mountain, dark crater floors |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Parent planet and sibling moons
Frequently asked
- How big is Oberon?
- 1,523 km.
- How far is Oberon from Earth?
- 583,500 km.
- What is notable about Oberon?
- 11-km mountain, dark crater floors.
- Which planet does Oberon orbit?
- Uranus.
Hamlet crater and a map written in Shakespeare
Oberon's features carry the names of male characters from Shakespeare's tragedies. The largest crater, 206 km across, is Hamlet, with Othello, Macbeth, Lear, Romeo and Falstaff around it; chasms take place names from the plays, Mommur Chasma chief among them. The naming rules for Uranian moons, set by the International Astronomical Union, assign each moon its own works and gender of characters.
The floor of Hamlet crater holds a pool of dark material that stood out in Voyager's images. One reading is that the impact punched through the crust and dark carbonaceous material welled up; another is that a cryovolcano erupted a dark water–ammonia mix. The 11 km mountain on Oberon's limb stands near this dark deposit, and it would be among the first targets for a Uranus orbiter.
The moon in depth
Oberon was discovered by William Herschel on 11 January 1787, the same night as Titania, and named for the fairy king of A Midsummer Night's Dream. At 1,523 km across it is slightly smaller than Titania and orbits 583,500 km from Uranus every 13.5 days — the only major moon that travels outside the planet's magnetosphere, largely untouched by its radiation.
Voyager 2 imaged only Oberon's southern hemisphere in 1986. The surface is the most heavily cratered of the Uranian moons, and an 11-km mountain was spotted in silhouette on the limb. The floors of the largest craters are coated in very dark material, thought to be icy lava that welled up from inside and darkened as it mixed with organic compounds.
Follow Uranus in the orbit view and zoom out to find Oberon plodding around the outermost of the five large moons. Because the planet lies on its side, each pole faces the Sun for 42 years at a time, and each hemisphere of Oberon likewise endures decades of daylight and darkness in turn.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.