Cressida_(moon)
Cressida (moon)
Moon of Uranus
Cressida /ˈkrɛsədə/ is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 9 January 1986, and was given the temporary designation S/1986 U 3.[8] It was named after Cressida, the Trojan daughter of Calchas, a tragic heroine who appears in William Shakespeare's play Troilus and Cressida (as well as in tales by Geoffrey Chaucer and others). It is also designated Uranus IX.[9]
- There is also an asteroid called 548 Kressida.
Cressida belongs to the Portia group of satellites, which includes Bianca, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita.[6] These satellites have similar orbits and photometric properties.[6] Other than its orbit,[3] size of 92 × 74 km[4] and geometric albedo of 0.08,[6] virtually nothing is known about it.
In the Voyager 2 images Cressida appears as an elongated object, its major axis pointing towards Uranus. The ratio of axes of Cressida's prolate spheroid is 0.8 ± 0.3.[4] Its surface is grey in color.[4]
Cressida orbits close to a 3:2 resonance with the η ring, one of the rings of Uranus. Perturbations of the ring's shape provide a way to measure the mass of Cressida, which in 2024 was found to be (1.839±0.212)×1017 kg.[5] Cressida is one of the few small satellites of Uranus for which the mass has been directly measured.[10][5]
Cressida may collide with Desdemona within the next 100 million years.[11]