Perdita (moon)

Perdita is a closer moon to Uranus. Perdita's discovery was not simple. The first pictures of Perdita were taken by the Voyager 2 spacecraft in 1986, but it was not seen on the photographs for more than ten years. In 1999, the moon was noticed and reported.[1][4]

Perdita
Discovery
Discovered byErich Karkoschka / Voyager 2
Discovery dateMay 18, 1999 (in images dating back to January 18, 1986)
Orbital characteristics
Mean orbit radius
76,417 ± 1 km[1]
Eccentricity0.0012 ± 0.0005[1]
0.638021 ± 0.000013 d[1]
Inclination0.0 ± 0.3° (to Uranus' equator)[1]
Satellite ofUranus
Physical characteristics
Dimensions30 × 30 × 30 km[1]
Mean radius
15 ± 3 km[1]
~2,800 km²[2]
Volume~14,000 km³[2]
Mass~0.18×1017 kg[2]
Mean density
~1.3 g/cm³ assumed
~0.0047 m/s2[2]
~0.011 km/s[2]
synchronous[1]
zero[1]
Albedo0.08 ± 0.01[3]
Temperature~64 K[2]

    Because no further pictures could be taken to confirm its existence, in 2001 it was thought to be non-existent.[5] However, in 2003, pictures taken by the Hubble Space Telescope managed to pick up an object where Perdita was supposed to be. This proved its existence at last.[6][7]

    After its discovery in 1999, Perdita was labelled S/1986 U 10.[4] she was the daughter of Leontes and Hermione in William Shakespeare's play The Winter's Tale. The moon is also called Uranus XXV.[8]

    Perdita belongs to Portia Group of moons, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind and Belinda.[3] These moons have similar orbits and photometric properties.[3] Unfortunately, other than its orbit,[1][6] radius of 15 km,[1] and geometric albedo of 0.08,[3] almost nothing is known about it.

    References
    1. Karkoschka, Erich (2001). "Voyager's eleventh discovery of a satellite of Uranus and photometry and the first size measurements of nine satellites". Icarus. 151 (1): 69–77. Bibcode:2001Icar..151...69K. doi:10.1006/icar.2001.6597.
    2. Calculated on the basis of other parameters
    3. Karkoschka, Erich (2001). "Comprehensive Photometry of the Rings and 16 Satellites of Uranus with the Hubble Space Telescope". Icarus. 151 (1): 51–68. Bibcode:2001Icar..151...51K. doi:10.1006/icar.2001.6596.
    4. Karkoschka, Erich (May 18, 1999). "IAU Circular No. 7171". Retrieved 2006-08-05.
    5. Foust, Jeff (2001). "Moon of Uranus is demoted". Spaceflight Now. Retrieved 2006-08-05.
    6. Showalter, Mark R.; Lissauer, Jack J. (December 22, 2005). "The Second Ring-Moon System of Uranus: discovery and dynamics". Science Express. 311 (5763): 973–977. doi:10.1126/science.1122882. PMID 16373533. S2CID 13240973.
    7. Showalter M. R. & Lissauer J.J. (September 3, 2003). "IAU Circular No. 8194". Retrieved 2006-08-05.
    8. "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. July 21, 2006. Retrieved 2006-08-05.

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