Uranus has 27 known moons.
The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787.
Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851.
In 1852, Herschel's son John Herschel gave the four then-known moons their names.
In 1948 Gerard Kuiper discovered the moon Miranda.
The flyby of the Voyager 2 space probe in January 1986 led to the discovery of a further 10 inner moons, and another satellite Perdita was later found after studying old Voyager photographs.
Two more small inner moons were discovered by astronomers using the Hubble Space Telescope.
Until 1997, Uranus was the only giant planet with no known irregular satellites.
Since then, nine distant irregular moons have been identified using ground-based telescopes.
The region between the main rings and Miranda appears to be very crowded.
The system is chaotic and apparently unstable, and simulations show that the moons may perturb each other into crossing orbits which may result in collisions between the moons.