Umbriel


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Umbriel

(ŭm`brēĕl'), in astronomy, one of the moons, or natural satellites, of UranusUranus
, in astronomy, 7th planet from the sun, at a mean distance of 1.78 billion mi (2.87 billion km), with an orbit lying between those of Saturn and Neptune; its period of revolution is slightly more than 84 years.
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Umbriel

(um -bree-ĕl) A satellite of Uranus, discovered in 1851 by William Lassell. Photographed by Voyager 2 in 1986, it is very dark with an albedo of only 0.18. It is heavily cratered, its most prominent feature being Skyund, a crater 100 km in diameter with a bright central peak. See also Uranus' satellites; Table 2, backmatter.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Umbriel

 

a satellite of the planet Uranus. Umbriel has a diameter of about 1,000 km and is at a mean distance of 267,000 km from the center of the planet. The satellite was discovered in 1851 by W. Lassell. The orbital plane of Umbriel is nearly perpendicular to the orbital plane of Uranus.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

Umbriel

[′əm·brē·əl]
(astronomy)
A satellite of Uranus orbiting at a mean distance of 165,300 miles (266,000 kilometers) with a period of 4.144 days, and with a diameter of about 740 miles (1190 kilometers).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Now the gnome Umbriel replaces Ariel as Belinda's guardian spirit, indicating that she has changed from being a coquette to being a prude.
But Umbriel, one of Uranus' five large moons, doesn't fit the pattern.
Umbriel, a spirit who takes over when Ariel leaves Belinda.
Uranus moons, Body mass M, kg ln(M/ [DELTA] sorted by M [m.sub.p]) Miranda 6.5900 x [10.sup.19] 107.2916 1.2551 Umbriel 1.1720 x [10.sup.21] 110.1700 1.2328 Ariel 1.3530 x [10.sup.21] 110.3136 1.2402 Oberon 3.0140 x [10.sup.21] 111.1145 1.2446 Titania 3.5270 x [10.sup.21] 111.2717 1.2507 Uranus moons, ln(T/ Orbital Uranus moons sorted by M [[tau].sub.p]) period T, years sorted by T Miranda 67.3294 1.4135 Miranda Umbriel 67.9076 2.5200 Ariel Ariel 68.4050 4.1440 Umbriel Oberon 69.1473 8.7062 Titania Titania 69.5833 13.4632 Oberon
On the original image there is an indication above Uranus of Umbriel (14.8).
When Umbriel arrives, we learn that "Unnumber'd Throngs on ev'ry side are seen / Of Bodies chang'd to various Forms by Spleen" (4.47-48).
Umbriel, much darker than the four other major moons and "strikingly" uniform in its somber complexion, leaves scientists puzzling over the question of where all the dark material might have come from on the presumably ice-rich satellite.
The brightest moons of Uranus--Ariel, Umbriel, Titania, and Oberon--are about as bright as Triton except for Titania, magnitude 14.0.