List of natural satellites
Uranus has 27 named moons, five of which are massive enough to have achieved hydrostatic equilibrium. There are another 13 inner moons that orbit within Uranus's ring system, and another nine outer irregular moons. Unlike most planetary moons, which are named from antiquity, all the moons of Uranus are named after characters from the works of Shakespeare and Alexander Pope's work "The Rape of the Lock".
Voyager program
Data and photographs collected by the Voyagers' cameras, magnetometers and other instruments, revealed unknown details about each of the four giant planets and their moons. Close-up images from the spacecraft charted Jupiter's complex cloud forms, winds and storm systems and discovered volcanic activity on its moon Io. Saturn's rings were found to have enigmatic braids, kinks and spokes and to be accompanied by myriad "ringlets". At Uranus, "Voyager 2" discovered a substantial magnetic field around the planet and ten more moons. Its flyby of Neptune uncovered three rings and six hitherto unknown moons, a planetary magnetic field and complex, widely distributed auroras. "Voyager 2" is the only spacecraft to have visited the two ice giants. In August 2018, NASA confirmed, based on results by the "New Horizons" spacecraft, of a "hydrogen wall" at the outer edges of the Solar System that was first detected in 1992 by the two Voyager spacecraft.