Cressida (moon)

There is also an asteroid called 548 Kressida.
Cressida
Enhanced Voyager 2 image of Cressida
Discovery
Discovered byStephen P. Synnott / Voyager 2
Discovery dateJanuary 9, 1986
Designations
Designation
Uranus IX
Pronunciation/ˈkrɛsədə/[1]
Named after
Χρησίδα
AdjectivesCressidian /krɛˈsɪdiən/[2]
Orbital characteristics[3]
61,766.730 ± 0.046 km
Eccentricity0.00036 ± 0.00011
0.463569601 ± 0.000000013 d
Inclination0.006 ± 0.040° (to Uranus' equator)
Satellite ofUranus
Physical characteristics
Dimensions92 × 74 × 74 km[4][note 1]
~20000 km2[a]
Volume263800±38.0% km3[5]
Mass(1.839±0.212)×1017 kg[5]
Mean density
0.70+0.44
−0.21 g/cm3[5]
~0.006–0.009 m/s2[a]
~0.023–0.026 km/s[a]
synchronous[4]
zero[4]
Albedo0.08±0.005[6]
0.07[7]
Temperature~65 K[a]
  1. ^ Only two dimensions are known; the third dimension has been assumed to equal the smaller known dimension.

Cressida /ˈkrɛsədə/ is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 9 January 1986, and was given the temporary designation S/1986 U 3.[8] It was named after Cressida, the Trojan daughter of Calchas, a tragic heroine who appears in William Shakespeare's play Troilus and Cressida (as well as in tales by Geoffrey Chaucer and others). It is also designated Uranus IX.[9]

Cressida belongs to the Portia group of satellites, which includes Bianca, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda, and Perdita.[6] These satellites have similar orbits and photometric properties.[6] Other than its orbit,[3] size of 92 × 74 km,[4] and geometric albedo of 0.08,[6] virtually nothing is known about it.

In Voyager 2 imagery Cressida appears as an elongated object, with its major axis pointing towards Uranus. The ratio of axes of Cressida's prolate spheroid is 0.8 ± 0.3.[4] Its surface is grey in color.[4]

Cressida orbits close to a 3:2 resonance with the η ring, one of the rings of Uranus. Perturbations of the ring's shape provide a way to measure the mass of Cressida, which in 2024 was found to be (1.839±0.212)×1017 kg.[5] Cressida is one of the few small satellites of Uranus for which the mass has been directly measured.[10][5]

Cressida may collide with Desdemona within the next 100 million years.[11]

  1. ^ Benjamin Smith (1903). The Century Dictionary and Cyclopedia.
  2. ^ Kellog (1995). Boccaccio's and Chaucer's Cressida.
  3. ^ a b Cite error: The named reference Jacobson 1998 was invoked but never defined (see the help page).
  4. ^ a b c d e f Cite error: The named reference Karkoschka, Voyager 2001 was invoked but never defined (see the help page).
  5. ^ a b c d e Cite error: The named reference FrenchEtAl2024 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Karkoschka, Hubble 2001 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Williams 2007 nssdc was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference IAUC 4164 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Gazetteer was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eta-ring was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Duncan Lissauer 1997 was invoked but never defined (see the help page).


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