Perdita (moon)

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Discovered byErich Karkoschka / Voyager 2
Discovery dateMay 18, 1999 (in images dating back to January 18, 1986)
Avgdistance from the center of its orbital path76,417 ± 1 km[1]
How long it takes to complete an orbit0.638021 ± 0.000013 d[1]
Angle above the reference plane
0.0 ± 0.3° (to Uranus' equator)[1]
What it orbitsUranus
Size and other qualities
Measurements30 × 30 × 30 km[1]
Average radius15 ± 3 km[1]
Surface area~2,800 km²[2]
Volume~14,000 km³[2]
Mass~0.18×1017 kg[2]
Average density~1.3 g/cm³ assumed
Surface gravity~0.0047 m/s2[2]
Escape velocity~0.011 km/s[2]
Rotation periodsynchronous[1]
Angle at which it turns
(in relation to its orbit)
How much light it reflects0.08 ± 0.01[3]
Avg. surface temp.~64 K[2]

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]

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[change | change source]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Karkoschka, Erich (2001). "Voyager's eleventh discovery of a satellite of Uranus and photometry and the first size measurements of nine satellites". Icarus 151: 69–77. doi:10.1006/icar.2001.6597. 
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Calculated on the basis of other parameters
  3. 3.0 3.1 3.2 3.3 Karkoschka, Erich (2001). "Comprehensive Photometry of the Rings and 16 Satellites of Uranus with the Hubble Space Telescope". Icarus 151: 51–68. doi:10.1006/icar.2001.6596. 
  4. 4.0 4.1 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. 6.0 6.1 Showalter, Mark R.; Lissauer, Jack J. (December 22, 2005). "The Second Ring-Moon System of Uranus: discovery and dynamics". Science Express. doi:10.1126/science.1122882. 
  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.

Other websites[change | change source]