Perdita (moon)


Perdita feat.jpg
Discovered byErich Karkoschka / Voyager 2
Discovery dateMay 18, 1999 (in images dating back to January 18, 1986)
Uranus XXV
AdjectivesPerditean /pɜːrdəˈtən/[2]
Orbital characteristics
Mean orbit radius
76,417 ± 1 km[3]
Eccentricity0.0012 ± 0.0005[3]
0.638021 ± 0.000013 d[3]
Inclination0.0 ± 0.3° (to Uranus' equator)[3]
Satellite ofUranus
Physical characteristics
Dimensions30 × 30 × 30 km[3]
Mean radius
15 ± 3 km[3]
~2,800 km2[a]
Volume~14,000 km3[a]
Mass~0.18×1017 kg[a]
Mean density
~1.3 g/cm3 (assumed)
~0.0047 m/s2[a]
~0.011 km/s[a]
Albedo0.08 ± 0.01[4]
Temperature~64 K[a]

Perdita /ˈpɜːrdətə/ is an inner satellite of Uranus. Perdita's discovery was complicated. 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.[3][5] But because no further pictures could be taken to confirm its existence, it was officially demoted in 2001.[6] 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.[7][8]

Following its discovery in 1999, it was given the temporary designation of S/1986 U 10.[5] It was named Perdita (Latin for 'lost') after the daughter of Leontes and Hermione in William Shakespeare's play The Winter's Tale. The moon is also designated Uranus XXV.[9]

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. It is also close to an 8:7 resonance with Rosalind.[3][7]

Perdita belongs to the Portia group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind and Belinda.[4] These satellites have similar orbits and photometric properties.[4] Little is known about Perdita apart from its orbit,[3][7] radius of 15 km[3] and geometric albedo of 0.08.[4]

See also


Explanatory notes

  1. ^ a b c d e f Calculated on the basis of other parameters.


  1. ^ Benjamin Smith (1903) The Century Dictionary and Cyclopedia
  2. ^ Byrne (2008) Perdita: the literary, theatrical, scandalous life of Mary Robinson
  3. ^ a b c d e f g h i j k l Karkoschka, Voyager 2001.
  4. ^ a b c d Karkoschka, Hubble 2001.
  5. ^ a b IAUC 7171.
  6. ^ Foust 2001.
  7. ^ a b c Showalter & Lissauer 2006.
  8. ^ IAUC 8194.
  9. ^ USGS: Planet and Satellite Names and Discoverers.


  • 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.
  • 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.
  • Green, Daniel W. E. (May 18, 1999). "S/1986 U 10". IAU Circular. 7171: 1. Bibcode:1999IAUC.7171....1K. ISSN 0081-0304. Retrieved 2012-01-26.
  • Foust, Jeff (December 31, 2001). "Moon of Uranus is demoted". Spaceflight Now. Retrieved 2012-01-26.
  • Showalter, Mark R.; Lissauer, Jack J. (2006-02-17). "The Second Ring-Moon System of Uranus: Discovery and Dynamics". Science. 311 (5763): 973–977. Bibcode:2006Sci...311..973S. doi:10.1126/science.1122882. PMID 16373533. S2CID 13240973.
  • Green, Daniel W. E. (September 3, 2003). "Satellites of Uranus". IAU Circular. 8194. ISSN 0081-0304. Retrieved 2012-01-26.
  • USGS/IAU (July 21, 2006). "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. Retrieved 2012-01-26.

External links

  • Uranus 'Loses' a Moon: The 'New' Official Moon Count of the Solar System (Archived), Melanie Melton, The Planetary Society, 20 December 2001