Cressida (moon)

There is also an asteroid called 548 Kressida.

Cressida

Voyager 2 image of the Uranian moons Portia, Cressida, and Ophelia
Discovery
Discovered by	Stephen P. Synnott / Voyager 2
Discovery date	January 9, 1986
Orbital characteristics
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
Proper orbital elements
Physical characteristics
Dimensions	92 × 74 × 74 km[2]
Mean radius	39.8 ± 2 km[2][3][4]
Surface area	~20,000 km²[a]
Volume	~260,000 km³[a]
Mass	~3.4×1017 kg[a]
Mean density	~1.3 g/cm³ (assumed)[3]
Equatorial surface gravity	~0.013 m/s2[a]
Escape velocity	~0.034 km/s[a]
Rotation period	synchronous[2]
Axial tilt	zero[2]
Albedo	0.08 ± 0.01[5] 0.07[3][4]
Temperature	~64 K[a]

Cressida ( /ˈkrɛsɨdə/ kres-i-də) 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.^[6] 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.^[7]

Cressida belongs to the Portia Group of satellites, which includes Bianca, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita.^[5] These satellites have similar orbits and photometric properties.^[5] Unfortunately, other than its orbit,^[1] radius of 41 km^[2] and geometric albedo of 0.08^[5] 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 axes 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.^[8]

See also

• Moons of Uranus

References

Explanatory notes

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

Citations

1. ^ ^{a b c d e} Jacobson, R. A. (1998). "The Orbits of the Inner Uranian Satellites From Hubble Space Telescope and Voyager 2 Observations". The Astronomical Journal 115 (3): 1195–1199. Bibcode 1998AJ....115.1195J. doi:10.1086/300263.  edit
2. ^ ^{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 (1): 69–77. Bibcode 2001Icar..151...69K. doi:10.1006/icar.2001.6597.  edit
3. ^ ^{a b c} "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 24 October 2008. http://ssd.jpl.nasa.gov/?sat_phys_par. Retrieved 12 December 2008. 
4. ^ ^{a b} Williams, Dr. David R. (23 November 2007). "Uranian Satellite Fact Sheet". NASA (National Space Science Data Center). http://nssdc.gsfc.nasa.gov/planetary/factsheet/uraniansatfact.html. Retrieved 12 December 2008. 
5. ^ ^{a b c d} Karkoschka, E. (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.  edit
6. ^ Smith, B. A. (January 16, 1986). "Satellites of Uranus". IAU Circular 4164. http://www.cbat.eps.harvard.edu/iauc/04100/04164.html#Item1. Retrieved 29 October 2011. 
7. ^ "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. July 21, 2006. http://planetarynames.wr.usgs.gov/append7.html. Retrieved 6 August 2006. 
8. ^ Duncan, Martin J.; Lissauer, Jack J. (1997). "Orbital Stability of the Uranian Satellite System". Icarus 125 (1): 1–12. Bibcode 1997Icar..125....1D. doi:10.1006/icar.1996.5568.  edit

External links

• Cressida Profile by NASA's Solar System Exploration
• Uranus' Known Satellites (by Scott S. Sheppard)