Space Topics: Uranus
Uranus' Moons
Like all the outer planets, Uranus is surrounded by a swarm of moons -- 27,
at current count. Five are large icy satellites that were discovered
prior to the Space Age; 10 by Voyager 2 in 1986; and the rest in telescopic
surveys since 1997. The orbits of the moons are intimately mixed among
Uranus' extended ring system. The whole system is now thought to be chaotic,
with the orbits changing rapidly over time. The
estimated sizes of the smaller moons have changed over time as surveys
have improved our knowledge of their physical properties.
Although Voyager 2 performed a survey of Uranus’ moons, it passed by
when tilted Uranus was at the height of southern summer. As a result,
only the southern hemispheres of Uranus’ moons have ever been imaged
by spacecraft. Additionally, the “bull’s-eye” pattern
of Uranus’ rings and moons on the sky meant that Voyager 2 saw only
Miranda close-up; the rest of the moons were only seen distantly.
Inner Small Moons
Uranus rings and shepherds
Voyager 2 discovered that Uranus' brightest Epsilon ring is shepherded by
two satellites, Cordelia (1986U7) and Ophelia (1986U8), each only about 40
kilometers in diameter. Credit: NASA/JPL
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Moons of Uranus discovered by Voyager 2
Three moons discovered by Voyager 2 lie outside the ring system in this view
from January 18, 1986. The moons are Portia (1986U1), Cressida (1986 U3), and
Rosalind (1986 U4). Credit: NASA/JPL
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Cordelia
40 kilometers diameter
49,800 kilometers from Uranus
Inner shepherd of the Epsilon Ring.
Ophelia
42 kilometers diameter
53,800 kilometers from Uranus
Outer shepherd of the Epsilon Ring.
Bianca
51 kilometers diameter
59,200 kilometers from Uranus
Cressida
80 kilometers diameter
61,800 kilometers from Uranus
Desdemona
64 kilometers diameter
62,700 kilometers from Uranus
Juliet
93 kilometers diameter
64,400 kilometers from Uranus
Portia
135 kilometers diameter
66,100 kilometers from Uranus
Rosalind
72 kilometers diameter
69,900 kilometers from Uranus
Cupid (S/2003 U2)
10 kilometers diameter
74,800 kilometers from Uranus
Belinda
80 kilometers diameter
75,300 kilometers from Uranus
Perdita (S/2003 U10)
20 kilometers diameter
76,420 kilometers from Uranus
Puck
162 kilometers diameter
86,000 kilometers from Uranus
Mab (S/2003 U1)
10 kilometers diameter
97,734 kilometers from Uranus
Major Moons
Miranda
471 kilometers diameter
129,900 kilometers from Uranus
Ariel
1,158 kilometers diameter
190,900 kilometers from Uranus
Umbriel
1,169 kilometers diameter
266,000 kilometers from Uranus
Titania
1,578 kilometers diameter
436,300 kilometers from Uranus
Oberon
1,522 kilometers diameter
583,500 kilometers from Uranus
Outer Small Moons
S/2001 U3
22 kilometers diameter
4,276,000 kilometers from Uranus
Caliban
72 kilometers diameter
7,231,000 kilometers from Uranus
Stephano
32 kilometers diameter
8,004,000 kilometers from Uranus
Trinculo
18 kilometers diameter
8,504,000 kilometers from Uranus
Sycorax
150 kilometers diameter
12,179,000 kilometers from Uranus
S/2003 U3
20 kilometers diameter
14,345,000 kilometers from Uranus
Prospero
50 kilometers diameter
16,256,000 kilometers from Uranus
Setebos
47 kilometers diameter
17,418,000 kilometers from Uranus
S/2001 U2
21 kilometers diameter
20,901,000 kilometers from Uranus
Check these sites for the most up-to-date facts on Neptune’s small
satellites.
Scott
Sheppard's Uranus Satellite Page
NASA's Solar System Dynamics pages: Satellite
Properties and Satellite
Elements
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Miranda
Ariel
Umbriel
Titania
Oberon
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