Caliban and Sycorax

Updated May 8, 2019 | Infoplease Staff

In 1997, two new moons, the first with irregular, noncircular orbits, were discovered around Uranus. Caliban has a diameter of 37 mi (60 km) and orbits Uranus at an average distance of 4.5 million miles (7.2 million kilometers). Sycorax has a diameter of 74.5 mi (120 km) and a much more elliptical orbit than Caliban, bringing it as close as 3.7 million miles (6 million km) to the planet.