Miranda

Miranda is one of Uranus’s moons. It was discovered in 1948 by the Dutch-American astronomer Gerard Peter Kuiper.

Miranda is the smallest and innermost of Uranus’s five major moons. Uranus has five major satellites and 22 minor satellites, according to NASA. The major five moons were discovered by direct observations from Earth, eleven others were discovered by the Voyager 2 spacecraft mission in 1985-86 and the remainder by sensitive charge-coupled-device (CCD) detectors on Earth.

All of the moons of Uranus get their names from characters from the works of William Shakespeare or Alexander Pope. The name Miranda comes from the name of the daughter of the old Duke Prospero in Shakespeare’s “The Tempest”. Gerard Peter Kuiper chose the name in his report of the moon’s discovery. It is also designated Uranus V.

The composition of Miranda appears to be about half water-ice and half rock. Miranda’s surface features are unique in the Solar System. It looks in photographs as though it was glued together from different pieces of rock. There are densely cratered plains that may have originated from meteorite impacts. These terrains, in turn, are cut by a series of canyons and fault escarpments. There are four different groups of canyons. They are categorised according to width: 1 to 2 km; 15 to 20 km; 35 km (approx.); 80 km (approx.). The wider two canyons are asymmetrical, meaning that an escarpment on one side of the canyon is significantly higher than the opposing escarpment. The wider canyons may be between 6 and 8 km in depth. Some show terracing on their sides. There are also oval grooved features resembling a racetrack and called coronae.

The surface features may have been created by extensional forces caused by the upwelling of water ice from the moon’s interior as vast diapirs. These are mobile and ductile intrusions that force upwards through rocks or other material. This upwelling caused a change in the interior density distribution of the moon and reoriented the moon around its polar axis. A similar effect occurred on Enceladus, a moon of Saturn.

Miranda orbits synchronously around Uranus over an orbital period of 1.41 Earth days. This coincides with the rotational period of the moon on its own axis. The same hemisphere of Miranda always faces Uranus. Miranda rotates around its own axis at a highly inclined angle – over four degrees – to Uranus’ equatorial plane. Along with Uranus and its other satellites, Miranda takes 84 Earth years to orbit the sun.

The Voyager 2 spacecraft mission in 1986 photographed Uranus and its moons. Its closest approach to Miranda was at a distance of 147,000 km and the photographs had a resolution of 2.7 km. There have been no other missions to Uranus and its moons to date. After this flyby, astronomers proposed that Miranda had been shattered five times by collisions with meteorites and reassembled again by gravitational forces.