Outer moon of UranusThe outermost major moon
Oberon
Oberon is the most distant of Uranus's major moons, an old cratered world tinted by dark deposits.
- Host
- Uranus
- Type
- Icy moon
- Mean diameter
- 1,523 km
- Mean orbital radius
- 583,500 km
- Orbital period
- 13.46 days
- Surface gravity
- 0.346 m/s²
- Key feature
- Dark crater floors
- Discovered
- 1787 · William Herschel
Oberon up close
NASA imagery
Ancient terrain
Oberon has a heavily cratered surface with fewer obvious young resurfacing features than Titania. Dark patches on many crater floors may be organic-rich material or rock exposed after impacts.
Long faults and scarps record tectonic stress in the moon's ice shell. Some of these fractures may have opened during an early period of internal heating.
The edge of the system
Oberon is the outermost of Uranus's five major moons. It sits well beyond the planet's brighter rings and experiences a long seasonal cycle linked to Uranus's extreme axial tilt.
The Uranus system has been explored only during Voyager 2's rapid flyby. Higher-resolution observations of Oberon would help determine whether any subsurface liquid survived.
Worth knowing
Oberon is named after the king of the fairies in A Midsummer Night's Dream.
Its dark crater floors may contain some of the least reflective material in the Uranian system.
Oberon is about half the diameter of Earth's Moon.
Watch and explore
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Oberon: Icy Mysteries of Uranus's Moon Out Of Orbit
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Research & further reading
Mission imagery and measurements are interpreted alongside orbital data. Follow the source links for the current NASA overview and precise satellite parameters.