High Quality Content by WIKIPEDIA articles! Uranus, the seventh
planet of the Solar System, has 27 known moons, all of which are
named after characters from the works of William Shakespeare and
Alexander Pope. William Herschel discovered the first two moons,
Titania and Oberon, in 1787, and the remaining spherical moons were
discovered in 1851 by William Lassell (Ariel and Umbriel) and in
1948 by Gerard Kuiper (Miranda). The remaining moons were
discovered after 1985, either during the Voyager 2 flyby mission or
with the aid of advanced ground-based telescopes. Uranian moons are
divided into three groups: thirteen inner moons, five major moons,
and nine irregular moons. The inner moons are small dark bodies
that share common properties and origins with the planet's
rings. The five major moons are massive enough to have achieved
hydrostatic equilibrium, and four of them show signs of internally
driven processes such as canyon formation and volcanism on their
surfaces. The largest of these five, Titania, is 1,578 km in
diameter and the eighth-largest moon in the Solar System, and about
20 times less massive than Earth's Moon.
