As is the case for all other planets in the solar system, a naming system has been established for the planet Uranus, under which the names for all newly discovered moons must be drawn from a single literary category. Unlike all other planetary moon systems, however, the moons of Uranus are not named after figures in ancient Greco-Roman mythology, but instead are drawn from the works of English poets and playwrights like William Shakespeare and Alexander Pope.
Uranus was discovered by William Herschel in 1781. In subsequent years, Herschel went on to discover two of its moons, now called Titania and Oberon. Herschel also believed he had discovered additional moons, which were never confirmed by other astronomers. It was not until the 1850s that two more moons of Uranus, now Ariel and Umbriel, were observed by William Lassell. At that time, however, the moons had not been named. In the scientific literature they were referred to simply by Roman numerals: Titania was Uranus II, Oberon was Uranus IV, and so on.
It was only after Lassell's discovery of Ariel and Umbriel that another astronomer - John Herschel, whose father had discovered the planet in the previous century - published a naming system for the moons. The already discovered moons of Jupiter and Saturn had - like the planets themselves - been given names taken from Greek and Roman mythology. These two men instead turned to English literature for inspiration. Herschel named his father's moons after characters in William Shakespeare's play "A Midsummer Night's Dream." Lassell named his two moons after characters in "The Rape of the Lock," by English poet Alexander Pope.
Herschel and Lassell never publicly explained their decision not to use Greco-Roman names. David Palmer and Laura Whitlock of NASA explain that "sometimes they (astronomers) tried to mythologically match moon names to planet names, but there is no rule that this must be done." Conventionally, the right to name celestial objects belonged to those who discover them, and provided the names were generally accepted by other astronomers, there was no formal requirement to provide an explanation. Dutch astronomer Gerald Kuiper honoured the convention and continued with Lassell's and Herschel's tradition by assigning the name Miranda (from Shakespeare's "The Tempest") to Uranus's fifth moon, which he discovered in 1949.
Today, the rules for naming moons are somewhat different: Since the 1970s, all names must be approved by a committee of the International Astronomical Union, called the Working Group for Planetary System Nomenclature. The Working Group now requires that name proposals follow the established conventions for each planet. There are currently 27 known moons of Uranus, all of which have been officially named by the Working Group. Among the gas giants, this is the smallest moon system. (The largest is Jupiter's, with a total of 67 known moons.)
In that time, only one more moon, Belinda (discovered in 1986), has been named after a character from Pope's work. All of the others are named after Shakespearean characters. The Tempest has been the most popular source for inspiration, and has been used for the naming of the moons Caliban, Sycorax, Prospero, Setebos, Stephano, Trinculo, Francisco and Ferdinand. However, astronomers have also turned to most of Shakespeare's best-known works for inspiration: Puck comes from "A Midsummer Night's Dream" (the same play from which Herschel took the names Titania and Oberon), Ophelia from "Hamlet," Cordelia from "King Lear," Cressida from "Troilus and Cressida," Bianca from "The Taming of the Shrew," Desdemona from "Othello," Juliet and Mab from "Romeo and Juliet," Portio from "The Merchant of Venice," Rosalind from "As You Like It," Perdita from "The Winter's Tale" and Cupid from "Timon of Athens."