Perdita (moon)

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Perdita feat.jpg
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[1]
Eccentricity 0.0012 ± 0.0005[1]
0.638021 ± 0.000013 d[1]
Inclination 0.0 ± 0.3° (to Uranus' equator)[1]
Satellite of Uranus
Physical characteristics
Dimensions 30 × 30 × 30 km[1]
Mean radius
15 ± 3 km[1]
~2,800 km² [a]
Volume ~14,000 km³ [a]
Mass ~0.18×1017 kg[a]
Mean density
~1.3 g/cm³ (assumed)
~0.0047 m/s²[a]
~0.011 km/s[a]
Albedo 0.08 ± 0.01[2]
Temperature ~64 K[a]

Perdita (/ˈpɜːrdɪtə/ 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 the 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]

See also[edit]


Explanatory notes

  1. ^ a b c d e f Calculated on the basis of other parameters.



External links[edit]