Titania (moon) to have been shaped by both impacts and endogenic processes. It is covered with numerous impact craters reaching up to in diameter, but is less heavily cratered than Oberon, outermost of the five large moons of Uranus. Titania probably underwent an early endogenic resurfacing event which obliterated its older, heavily cratered surface. Titania's surface is cut by a system of enormous canyons and scarps, the result of the expansion of its interior during the later stages of its evolution. Like all major moons of Uranus, Titania probably formed from an accretion disk which surrounded the planet just after its formation.
Definition of planet object can be irregular in shape, but beyond that point gravity begins to pull an object towards its own centre of mass until the object collapses into an ellipsoid. (None of the large objects of the Solar System are truly spherical. Many are spheroids, and several, such as the larger moons of Jupiter and Saturn and the dwarf planet , have been further distorted into ellipsoids by rapid rotation or tidal forces, but still in hydrostatic equilibrium.) However, there is no precise point at which an object can be said to have reached hydrostatic equilibrium. As Soter noted in his