Perdita (moon)
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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 [a] |
| Volume | ~14,000 km³ [a] |
| Mass | ~0.18×1017 kg[a] |
| Mean density | ~1.3 g/cm³ (assumed) |
| Equatorial surface gravity | ~0.0047 m/s² [a] |
| Escape velocity | ~0.011 km/s[a] |
| Rotation period | synchronous[1] |
| Axial tilt | zero[1] |
| Albedo | 0.08 ± 0.01[2] |
| Temperature | ~64 K[a] |
Perdita (
/ˈpɜrdɨtə/ PUR-di-tə) 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.[1][3] But because no further pictures could be taken to confirm its existence, it was officially demoted in 2001.[4] 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.[5][6]
Following its discovery in 1999, it was given the temporary designation of S/1986 U 10.[3] 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.[7]
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.[1][5]
Perdita belongs to Portia Group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind and Belinda.[2] These satellites have similar orbits and photometric properties.[2] Little is known about Perdita apart from its orbit,[1][5] radius of 15 km[1] and geometric albedo of 0.08.[2]
[edit] See also
[edit] References
Explanatory notes
Citations
Sources
- 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. ISSN 0081-0304. http://www.cbat.eps.harvard.edu/iauc/07100/07171.html. Retrieved 2012-01-26.
- Foust, Jeff (December 31, 2001). "Moon of Uranus is demoted". Spaceflight Now. http://spaceflightnow.com/news/n0112/31uranusmoon/. 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.
- Green, Daniel W. E. (September 3, 2003). "Satellites of Uranus". IAU Circular 8194. ISSN 0081-0304. http://www.cbat.eps.harvard.edu/iauc/08100/08194.html. Retrieved 2012-01-26.
- USGS/IAU (July 21, 2006). "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. http://planetarynames.wr.usgs.gov/Page/Planets#UranianSystem. Retrieved 2012-01-26.
[edit] External links
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