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Cressida (moon)

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Discovered byStephen P. Synnott / Voyager 2
Discovery timeJanuary 9, 1986
Avgdistance from the center of its orbital path61,766.730 ± 0.046 km[1]
How egg-shaped its orbit is
0.00036 ± 0.00011[1]
How long it takes to complete an orbit0.463569601 ± 0.000000013 d[1]
Angle above the reference plane
0.006 ± 0.040° (to Uranus' equator)[1]
What it orbitsUranus
Size and Other Qualities
Measures92 × 74 × 74 km[2]
Average distance from its center to its surface41 ± 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 timesynchronous[2]
Angle at which it turns
(in relation to its orbit)
How much light it reflects0.08 ± 0.01[4]
Avg. surface temp.~64 K[3]

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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