Miranda, the innermost and smallest of the major moons of the planet Uranus, was discovered in 1948 by the Dutch-born American
astronomer Gerard Kuiper. When Voyager 2 flew by Uranus on Jan. 24, 1986, Miranda was found to have a diameter of 484 km (301 mi); orbiting at a distance of 104,350 km (64,840 mi) above Uranus's cloud
surface, the moon takes 1.41 days to circle the
planet. Photographs revealed a bizarre surface in which old, heavily cratered terrain is interspersed with three nearly rectangular regions of younger terrain characterized by parallel, concentric grooves around their edges. The theory that this appearance resulted from the fragmentation and reassembly of materials is now doubted. More likely it was caused by upwellings from the interior as the result of tidal stretching and distortion by Uranus's gravitational pull.