7th Largest Moon of Uranus - Sycorax (23rd Moon outwards from Uranus)

Uranus is known to have nine irregular moons, which circle the planet at a distance much greater than that of Oberon, the furthest of the large moons.

Sycorax is the largest retrograde irregular satellite of Uranus and seventh overall of the Uranus' moons. Sycorax is the 39th largest moon in the Solar System currently known.

Discovery

Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns and John J. Kavelaars using the 200-inch Hale telescope, together with Caliban, the second largest retrograde irregular moon of Uranus.

Naming

The moon was given the temporary designation S/1997 U1.

Sycorax the moon was named after Sycorax, Caliban's mother in William Shakespeare's play The Tempest.

Sycorax, an unseen character in William Shakespeare's play The Tempest (1611), is a powerful witch and the mother of Caliban. Sycorax 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.

Stats

Diameter: ~150 km

Semi-major axis: 12,179,000 km

Orbital Period: -1288.28 days

Rotation Period: 3.6 hours

Orbit

Sycorax follows a distant orbit, more than 20 times further from Uranus than the furthest regular moon Oberon. Its orbit is retrograde, moderately inclined and eccentric.

The orbital parameters suggest that it may belong, together with Setebos and Prospero, to the same dynamic cluster, suggesting common origin.

Origin

All the irregular moons are probably captured objects that were trapped by Uranus soon after its formation.

Sycorax is hypothesized to be a captured object: it did not form in the accretionary disk, which existed around Uranus just after its formation.

The exact capture mechanism is not known, but capturing a moon requires the dissipation of energy. The possible capture processes include: gas drag in the protoplanetary disk, many-body interactions and the capture during the fast growth of the Uranus' mass (so called pull-down).

Physical characteristics

Sycorax's light red color differs from the gray of the other irregular moons, implying a different origin.

Nothing is known about the internal structure of Sycorax.

Exploration Status

No close-up image of Sycorax has been photographed.

No mission is planned in the foreseeable future.