With a diameter of about 150 km (assuming an albedo of 0.04), Sycorax is the largest of the irregular moons which orbit Uranus in the opposite direction from the regular
moons and the planet's rotation (known as a retrograde orbit). Sycorax orbits Uranus at a distance of more than 12 million km, over 20 times as far as Oberon, which is Uranus' most distant regular moon. Its orbital characteristics are similar to those of Setebos and Prospero, suggesting a possible common origin. But its light red color differs from the gray of the other two moons, implying a different origin.
Sycorax was discovered on 6 September 1997 by Philip D. Nicholson, Brett J. Gladman, Joseph A. Burns and John J. Kavelaars using the 200-inch Hale Telescope at Palomar Observatory. They discovered another Uranian moon at the same time, which was named Caliban after the son of Sycorax in Shakespeare's play.
How Sycorax Got its Name:
Originally called S/1997 U2, Sycorax was named for a witch who was the mother of Caliban in William Shakespeare's play, "The Tempest," and who has died before the action of the play begins. She had been banished to the same island in the Mediterranean to which Prospero was later banished and had been responsible for the unjust imprisonment and enslavement of the sprite Ariel, later freed by Prospero.
Moons of Uranus are named for characters in Shakespeare's plays and from Alexander Pope's "Rape of the Lock."