Perdita (moon)

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**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^[2]
Eccentricity	0.0012 ± 0.0005^[2]
Orbital period	0.638021 ± 0.000013 d^[2]
Inclination	0.0 ± 0.3° (to Uranus' equator)^[2]
Satellite of	Uranus
Physical characteristics
Dimensions	30 × 30 × 30 km^[2]
Mean radius	15 ± 3 km^[2]
Surface area	~2,800 km²^[3]
Volume	~14,000 km³^[3]
Mass	~0.18×10¹⁷ kg^[3]
Mean density	~1.3 g/cm³ assumed
Equatorial surface gravity	~0.0047 m/s²^[3]
Escape velocity	~0.011 km/s^[3]
Rotation period	synchronous^[2]
Axial tilt	zero^[2]
Albedo	0.08 ± 0.01^[4]
Temperature	~64 K^[3]

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.^[5]^[2] 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, Perdita was given the temporary designation of S/1986 U 10.^[5] 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.^[9]

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.^[2]^[7]

Perdita belongs to 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] Unfortunately, other than its orbit,^[2]^[7] radius of 15 km^[2] and geometric albedo of 0.08^[4] virtually nothing is known about it.

References

^ [1]
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l
^ ^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:10.1006/icar.2001.6596.
^ ^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. doi:10.1126/science.1122882.
^ 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.

External links

Perdita Profile by NASA's Solar System Exploration

v • d • e Uranus
Major Moons	Ariel · Miranda · Oberon · Titania · Umbriel
Characteristics	Atmosphere · Rings of Uranus · Moons
Discovery	William Herschel · William Lassell
Exploration	Voyager program · Voyager 2
Other	15 Orionis · Uranus-crosser asteroid · In fiction