oberon

Oberon is the second largest moon of Uranus. Discovered in 1787, little was known about this moon until Voyager 2 passed it during its flyby of Uranus in January 1986. Oberon is heavily cratered―similar to Umbriel―especially when compared to three other moons of Uranus: Ariel, Titania and Miranda. Like all of Uranus' large moons, Oberon is composed of roughly half ice and half rock. Oberon has at least one large mountain that rises about 6 km off the surface.