Perdita (moon)

Perdita

Discovery
Discovered by	Erich Karkoschka / Voyager 2
Discovery date	May 18, 1999 (in images dating back to January 18, 1986)
Orbital characteristics
Mean orbit radius	76,417 ± 1 km
Eccentricity	0.0012 ± 0.0005
Orbital period (sidereal)	0.638021 ± 0.000013 d
Inclination	0.0 ± 0.3° (to Uranus' equator)
Satellite of	Uranus
Physical characteristics
Dimensions	30 × 30 × 30 km
Mean radius	15 ± 3 km
Surface area	~2,800 km²
Volume	~14,000 km³
Mass	~0.18×1017 kg
Mean density	~1.3 g/cm³ (assumed)
Surface gravity	~0.0047 m/s²
Escape velocity	~0.011 km/s
Synodic rotation period	synchronous
Axial tilt	zero
Albedo	0.08 ± 0.01
Temperature	~64 K

Perdita (/ˈpɜːrdtə/ 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. But because no further pictures could be taken to confirm its existence, it was officially demoted in 2001. 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.

Following its discovery in 1999, it was given the temporary designation of S/1986 U 10. 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.

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.

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

See also

• Moons of Uranus

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. Retrieved 2012-01-26.
• Foust, Jeff (December 31, 2001). "Moon of Uranus is demoted". Spaceflight Now. Retrieved 2012-01-26. {{cite web}}: Invalid |ref=harv (help)
• 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. {{cite journal}}: Invalid |ref=harv (help)
• 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

• Perdita Profile by NASA's Solar System Exploration