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,
Dysnomia (moon) pronounces the same as his wife's nickname, Di. Because of this, Brown pronounces the full name , with a long "y". Dysnomia serves as the extraterrestrial origin of the alien antagonist in the independent horror/comedy short film, "Skinhead Junkies From Dysnomia". Dysnomia (moon) Dysnomia (Greek: "Δυσνομία")—officially (136199) Eris I Dysnomia—is the only known moon of the dwarf planet Eris (the most massive known dwarf planet in the Solar System). It was discovered in 2005 by Mike Brown and the laser guide star adaptive optics team at the W. M. Keck Observatory, and carried the provisional designation of until officially named