Oberon (moon) geological feature on Oberon: craters and chasmata ('canyons'—deep, elongated, steep-sided depressions which would probably be described as rift valleys or escarpments if on Earth). Oberon's surface is the most heavily cratered of all the Uranian moons, with a crater density approaching saturation—when the formation of new craters is balanced by destruction of old ones. This high number of craters indicates that Oberon has the most ancient surface among Uranus's moons. The crater diameters range up to 206 kilometers for the largest known crater, Hamlet. Many large craters are surrounded by bright impact ejecta (rays) consisting of relatively fresh ice. The
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