Miranda

Miranda is the smallest and innermost of Uranus's five major moons. It was the fifth satellite of Uranus to be discovered; it was found by Gerard Kuiper in 1948, and named after the character Miranda in William Shakespeare's play, "The Tempest". Miranda orbits Uranus at a distance of 80,000 miles (129,000 km), with an orbital period of 1.41 days. Miranda's orbital inclination (4.34°) is unusually high - more than 10 times that of the other large Uranian moons.

Miranda, just 300 mi (480 km) across, is the smallest of Uranus's five major satellites. However, it is the one that was approached the closest by Voyager 2, and it turned out to have the most remarkable surface of all five. Miranda's surface is unlike anything else in the solar system, with mixture of old and young regions jumbled together in a haphazard fashion. It displays huge fault canyons up to 12 miles (20 km) deep, terraced layers, and ridges. The younger regions might have been produced by a partial melting of Miranda's interior, allowing lighter material to upwell to the surface.

One theory, proposed shortly after the Voyager 2 flyby, was that Miranda may have been shattered as many as five times during its evolution. After each shattering, the moon would have reassembled itself with portions of the core exposed and portions of the surface buried. Today, Miranda's past geological activity is believed to have been driven by tidal heating at a time when Miranda was captured in a 3:1 orbital resonance with Umbriel, and its orbit was more eccentric than it is currently. Miranda subsequently escaped this resonance; the escape mechanism explains why its orbital inclination is so much greater than Uranus's other large moons'.