Cressida (moon)

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Cressida
Discovery
Discovered by Stephen P. Synnott / Voyager 2
Discovery time January 9, 1986
Orbit
Avgdistance from the center of its orbital path 61,766.730 ± 0.046 km[1]
How egg-shaped its orbit is
("eccentricity")
0.00036 ± 0.00011[1]
How long it takes to complete an orbit 0.463569601 ± 0.000000013 d[1]
Angle above the reference plane
("inclination")
0.006 ± 0.040° (to Uranus' equator)[1]
What it orbits Uranus
Size and Other Qualities
Measures 92 × 74 × 74 km[2]
Average distance from its center to its surface 41 ± 2 km[2]
Area of its surface ~20,000 km²[3]
Volume inside it ~260,000 km³[3]
Mass ~3.4×1017 kg[3]
Average density ~1.3 g/cm³ (assumed)
Gravity at its surface ~0.013 m/s2[3]
Slowest speed able to escape into space
("escape velocity")
~0.034 km/s[3]
How long it takes to turn around one time synchronous[2]
Angle at which it turns
(in relation to its orbit)
zero[2]
How much light it reflects 0.08 ± 0.01[4]
Avg. surface temp. ~64 K[3]
Uranus-Portia-Cressida-Ophelia-NASA.gif

Cressida is a closer moon to Uranus. It was found from the images taken by Voyager 2 on 1986-01-09, and was given the 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 moons, which also includes Bianca, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita.[4] These moons have similar orbits and photometric properties.[4] Other than its orbit,[1] radius of 41 km[2] and geometric albedo of 0.08[4] almost nothing is known about it.

At the Voyager 2 images Cressida appears as a stretched 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]

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