Perdita (moon)
From Wikipedia, the free encyclopedia
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Discovery
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| Discovered by | Erich Karkoschka / Voyager 2 |
| Discovery date | May 18, 1999 (in images dating back to January 18, 1986) |
| Mean orbit radius | 76,417 ± 1 km[1] |
| Eccentricity | 0.0012 ± 0.0005[1] |
| Orbital period | 0.638021 ± 0.000013 d[1] |
| Inclination | 0.0 ± 0.3° (to Uranus' equator)[1] |
| Satellite of | Uranus |
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Physical characteristics
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| Dimensions | 30 × 30 × 30 km[1] |
| Mean radius | 15 ± 3 km[1] |
| Surface area | ~2,800 km²[2] |
| Volume | ~14,000 km³[2] |
| Mass | ~0.18×1017 kg[2] |
| Mean density | ~1.3 g/cm³ assumed |
| Equatorial surface gravity | ~0.0047 m/s2[2] |
| Escape velocity | ~0.011 km/s[2] |
| Rotation period | synchronous[1] |
| Axial tilt | zero[1] |
| Albedo | 0.08 ± 0.01[3] |
| Temperature | ~64 K[2] |
Perdita (pər'-di-tə, IPA: /ˈpɝdɨtə/) 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.[4][1] But because no further pictures could be taken to confirm its existence, it was officially demoted in 2001.[5] 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.[6][7]
Following its discovery in 1999, Perdita was given the temporary designation of S/1986 U 10.[4] It was named after the daughter of Leontes and Hermione in William Shakespeare's play The Winter's Tale. The moon is also designated Uranus XXV.[8]
The moon orbits between Belinda and Puck. The abovementioned 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.[1][6]
Perdita belongs to Portia Group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind and Belinda.[3] These satellites 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] virtually nothing is known about it.
[edit] References
- ^ a b c d e f g h i j k l 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:.
- ^ a b c d e f Calculated on the basis of other parameters
- ^ a b c d Karkoschka, Erich (2001). "Comprehensive Photometry of the Rings and 16 Satellites of Uranus with the Hubble Space Telescope". Icarus 151: 51–68. doi:.
- ^ a b Karkoschka, Erich (May 18 1999). IAU Circular No. 7171. Retrieved on 2006-08-05.
- ^ Foust, Jeff (December 31 2001). Moon of Uranus is demoted. Spaceflight Now. Retrieved on 2006-08-05.
- ^ a b c Showalter, Mark R.; Lissauer, Jack J. (2005-12-22). "The Second Ring-Moon System of Uranus: Discovery and Dynamics". Science Express 311: 973. doi:.
- ^ Showalter, M. R.; Lissauer, J. J. (September 3 2003). IAU Circular No. 8194. Retrieved on 2006-08-05.
- ^ Planet and Satellite Names and Discoverers. Gazetteer of Planetary Nomenclature. USGS Astrogeology (July 21 2006). Retrieved on 2006-08-05.
[edit] External links
Perdita Profile by NASA's Solar System Exploration
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