In the April 30, 1998, issue of the journal Nature, astronomers reported the discovery of two new moons of Uranus. The team of Philip Nicholson, Brett Gladman, Joseph Burns, and John Kavelaars, had first spotted the two satellites on Sept. 6, 1997, using the 200-inch Hale Telescope at the Palomar Observatory. In the April publication, the astronomers proposed naming the bodies Sycorax and Caliban, after characters in The Tempest.
The moons were the first at Uranus found in irregular orbits, and at the time of their discovery, the faintest moons imaged from Earth. Sycorax is approximately double the size of Caliban (75 miles [120 kilometers] and 37 miles [60 km] respectively); its orbit is also about double Caliban’s (3.5 years and 1.6 years, respectively). But both moons share the traits of irregular orbits, very low albedo, and a remarkably reddish tint. These characteristics suggest that they likely didn’t form around Uranus, but rather are Centaurs or trans-Neptunian objects captured by Uranus’ gravity.
