Cressida (moon)
From Wikipedia, the free encyclopedia
- There is also an asteroid called 548 Kressida.
|
Discovery
|
|
|---|---|
| Discovered by | Stephen P. Synnott / Voyager 2 |
| Discovery date | January 9, 1986 |
| Mean orbit radius | 61,766.730 ± 0.046 km[1] |
| Eccentricity | 0.00036 ± 0.00011[1] |
| Orbital period | 0.463569601 ± 0.000000013 d[1] |
| Inclination | 0.006 ± 0.040° (to Uranus' equator)[1] |
| Satellite of | Uranus |
|
Physical characteristics
|
|
| Dimensions | 92 × 74 × 74 km[2] |
| Mean radius | 41 ± 2 km[2] |
| Surface area | ~20,000 km²[3] |
| Volume | ~260,000 km³[3] |
| Mass | ~3.4×1017 kg[3] |
| Mean density | ~1.3 g/cm³ (assumed) |
| Equatorial surface gravity | ~0.013 m/s2[3] |
| Escape velocity | ~0.034 km/s[3] |
| Rotation period | synchronous[2] |
| Axial tilt | zero[2] |
| Albedo | 0.08 ± 0.01[4] |
| Temperature | ~64 K[3] |
Cressida (kres'-ə-də, IPA: /ˈkrɛsɨdə/) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 1986-01-09, and was given the temporary designation S/1986 U 3.[5] It was named after 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.[6]
Cressida belongs to Portia Group of satellites, which also includes Bianca, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita.[4] These satellites have similar orbits and photometric properties.[4] Unfortunately, other than its orbit,[1] radius of 41 km[2] and geometric albedo of 0.08[4] virtually nothing is known about it.
At the Voyager 2 images Cressida appears as an elongated object, the major axis pointing towards Uranus. The ratio of axises of the Cressida's prolate spheroid is 0.8 ± 0.3.[2] Its surface is grey in color.[2]
Cressida may collide with Desdemona within the next 100 million years.[7]
[edit] References
- ^ a b c d e Jacobson, R.A. (1998). "The Orbits of the Inner Uranian Satellites From Hubble Space Telescope and Voyager2 Observations". The Astronomical Journal 115: 1195-1199. doi:.
- ^ a b c d e f g Karkoschka, Erich (2001). "Voyager's Eleventh Discovery of a Satellite of Uranus and Photometry and the First Size Measurements of Nine Satellites". Icarus 151: 69–77. doi:.
- ^ 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:.
- ^ Smith, B. A. (January 16, 1986). IAU Circular No. 4164. Retrieved on 2006-08-06.
- ^ Planet and Satellite Names and Discoverers. Gazetteer of Planetary Nomenclature. USGS Astrogeology (July 21, 2006). Retrieved on 2006-08-06.
- ^ Duncan, Martin J.; Jack J. Lissauer (1997). "Orbital Stability of the Uranian Satellite System". Icarus 125 (1): 1-12. doi:.
[edit] External links
Cressida Profile by NASA's Solar System Exploration
|
|||||||||||||||||||
