Perdita/ˈpɜːrdətə/ is an inner satellite of Uranus. Perdita's discovery was very complicated, as the first photographs of Perdita were taken by the Voyager 2 spacecraft in 1986, but it was not recognized from the photographs for more than a decade. In 1999, the moon was noticed by Erich Karkoschka and reported.[4][9] But because no further pictures could be taken to confirm its existence, it was officially demoted in 2001.[10] However, in 2003, pictures taken by the Hubble Space Telescope managed to pick up an object where Perdita was supposed to be, finally confirming its existence.[8][11]
Discovery image of Perdita taken by Voyager 2 on 23 January 1986. The location of the moon is indicated by the arrow on the upper right.
The moon orbits between Belinda and Puck. The above-mentioned Hubble measurements prove that Perdita does not follow a direct Keplerian motion around Uranus. Instead, it is clearly caught in a 43:44 orbital resonance with the nearby moon Belinda, and from this resonance it has been determined that Belinda's mass is 26 times that of Perdita.[13] It is also close to an 8:7 resonance with Rosalind.[4][8]
Perdita belongs to the Portia group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind, and Belinda.[14] These satellites have similar orbits and photometric properties.[14] Little is known about Perdita apart from its orbit,[4][8] radius of 13.3 km,[5] and geometric albedo of 0.08.[14][8]
