Moons of Uranus these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about one-twentieth the mass the Earth's Moon. The orbits of the regular moons are nearly coplanar with Uranus's equator, which is tilted 97.77° to its orbit. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at large distances from the planet. William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other three ellipsoidal moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda). These five have planetary mass,
Titania (moon) Solar System. However, the color asymmetry of Titania is more likely related to accretion of a reddish material coming from outer parts of the Uranian system, possibly, from irregular satellites, which would be deposited predominately on the leading hemisphere. Scientists have recognized three classes of geological feature on Titania: craters, chasmata (canyons) and rupes (scarps). The surface of Titania is less heavily cratered than the surfaces of either Oberon or Umbriel, which means that the surface is much younger. The crater diameters reach 326 kilometers for the largest known crater, Gertrude (there can be also a degraded basin of approximately