Uranus has 27 moons, all of which are named after characters from the works of Shakespeare and Alexander Pope. The five main satellites, in order of proximity to Uranus, are Miranda, Ariel, Umbriel, Titania, and Oberon. Before the Voyager 2 studied Uranus in 1986, these five moons were the only ones known to exist.
Umbriel (a character in The Rape of the Lock by Pope) is the darkest moon of Uranus. It is also the least geologically active satellite with a heavily cratered surface indicating that it is old. Near the equator of Umbriel is a bright ring referred to the as the Fluorescent Cheerio or Wunda. The origin of this is unknown, though it is believed to be the floor of a crater.