[33] The polygons were identified from precise photometry of Voyager 2's images and are distributed more or less uniformly on the surface of Umbriel, trending northeast–southwest. Both northern and southern poles spend 42 years in complete darkness, and another 42 years in continuous sunlight, with the Sun rising close to the zenith over one of the poles at each solstice. [lower-alpha 6] The moon's density is 1.39 g/cm3,[4] which indicates that it mainly consists of water ice, with a dense non-ice component constituting around 40% of its mass. This hypothesis would explain the asymmetry in its distribution, as the trailing hemisphere is subject to a more intense magnetospheric influence than the leading hemisphere. UMBRIEL'S SURFACE IS HEAVILY CRATERED and is the darkest of the major Uranian moons.

Ariel, and possibly on Oberon. location to another. Umbriel has a diameter of 1,170 km (727 miles) and a density of about 1.4 grams per cubic cm. shading correction and contrast enhancement. [31], Much like other moons of Uranus, the surface of Umbriel is cut by a system of canyons trending northeast–southwest. have been smoothed by a fluid.

lit) because water acts like steel at these temperatures. There may be an asymmetry between the leading and trailing hemispheres; the former appears to be redder than the latter. The moon is also designated Uranus II. Water ice absorption …

[7], Except for water, the only other compound identified on the surface of Umbriel by the infrared spectroscopy is carbon dioxide, which is concentrated mainly on the trailing hemisphere.

Proteus (Neptune's Moon) - (Important Facts) {Part... Triton (Neptune's Moon) - (Important Facts) {Part-51}, Ariel (Uranus' Moon) - (Important Facts) {Part-50}, Titania (Uranus' Moon) - (Important Facts) {Part-48}, Oberon (Uranus' Moon) - (Important Facts) {Part-47}, Deimos (Mars' Moon) - (Important Facts) {Part-46}, Phobos (Mars' Moon) - (Important Facts) {Part-45}, Triassic Period (Important Facts) {Part-7}. represented as red and bright regions are represented as blue. Once every 42 years, when Uranus has an equinox and its equatorial plane intersects the Earth, mutual occultations of Uranus's moons become possible. The moon appears to be composed of equal parts water ice and rocky material, intermixed with small amounts of frozen methane. (Copyright Calvin J. Hamilton) nds:Umbriel (Maand)

While a co-orbiting population of dust particles is another possible source of the dark material, this is considered less likely because other satellites were not affected.

[25] The only signs of the ancient internal activity are canyons and dark polygons—dark patches with complex shapes measuring from tens to hundreds of kilometers across. (Courtesy A. Tayfun Oner) The largest fault valleys, near the terminator at right, as well [7], Umbriel may be differentiated into a rocky core surrounded by an icy mantle. scientists believe the valleys have formed over down-dropped [15] This bombardment may lead to the darkening of the trailing hemispheres, which is actually observed for all Uranian moons except Oberon (see below). (Courtesy A. Tayfun Oner). Umbriel is the darkest moon and Ariel the brightest. The surface is pock-marked with craters, Voyager surface long rift valleys extend. is not clear whether these sinuous features have been formed by This image is a mercator map of Ariel. [7] Water ice absorption bands are stronger on Umbriel's leading hemisphere than on the trailing hemisphere. (Courtesy A. Tayfun Oner) The surface of Umbriel [5] No other spacecraft has ever visited Uranus (and Umbriel), and no mission to Uranus and its moons are planned. unsmeared Voyager 2 images of Ariel were used in making this map. filled with deposits that are younger and less heavily cratered Umbriel is about the same size as Ariel and has nearly the same density. Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. sv:Umbriel [2] Its orbital period is around 4.1 Earth days, coincident with its rotational period.

They also state that the limited data also hint that the darker regions are Umbriel is the third largest and fourth most massive of Uranian moons.

(Credit: Calvin J. Hamilton) Similar ice volcanism is also seen on Miranda, It

In 2007–2008 a number of such events were observed including two occultations of Titania by Umbriel on August 15 and December 8, 2007 as well as of Ariel by Umbriel on August 19, 2007. All of Uranus's moons are named after characters created by William Shakespeare or Alexander Pope. [16], Because Uranus orbits the Sun almost on its side, and its moons orbit in the planet's equatorial plane, they (including Umbriel) are subject to an extreme seasonal cycle. [5], Umbriel is thought to have formed from an accretion disc or subnebula; a disc of gas and dust that either existed around Uranus for some time after its formation or was created by the giant impact that most likely gave Uranus its large obliquity. [26] The reddening of the surfaces probably results from space weathering from bombardment by charged particles and micrometeorites over the age of the Solar System. Although William Herschel, the discoverer of Titania and Oberon, claimed at the end of the 18th century that he had observed four additional moons of Uranus,his observations were not confirmed and those four objects are now thought to be spurious. The moon appears to be composed of equal parts water ice and rocky material, intermixed with small amounts of frozen methanesee

and 316 degrees longitude. Script error: The function "getCommonsLink" does not exist. fault scarps crisscross the highly pitted terrain. Umbriel Statistics MASSIVE STARS HAVE A MASS AT LEAST THREE TIMES that of the Sun , and some stars are as massive as about 50 Suns.

[5][30] Study of limb profiles of Umbriel revealed a possible very large impact feature having the diameter of about 400 km and depth of approximately 5 km. The pressure in the center of Umbriel is about 0.24 GPa (2.4 kbar). driven resurfacing event early in Umbriel's history involving darker [27] The surface of Umbriel has far more and larger craters than do Ariel and Titania and shows the least geological activity. [20][21], Umbriel is the third largest and fourth most massive of Uranian moons. Zero degrees longitude is located at the top. [7] The Voyager 2 flyby coincided with the southern hemisphere's 1986 summer solstice, when nearly the entire northern hemisphere was unilluminated. In the article [29][30] Wunda has a large ring of bright material on its floor, which appears to be an impact deposit. [24] However, the color asymmetry of Umbriel is likely caused by accretion of a reddish material coming from outer parts of the Uranian system, possibly, from irregular satellites, which would occur predominately on the leading hemisphere. The map covers from 70 to -70 degrees latitude with 0 degree longitude THE CARBONIFEROUS PERIOD (363-290 million years ago) takes its name from the thick, carbon-rich layers - now coal - that were produced  du... UMBRIEL'S SURFACE IS HEAVILY CRATERED and is the darkest of the major Uranian moons. Ariel [AIR-ee-al] is a relatively small satellite and is the

Zero degrees longitude is at the top. Albedo Map of Umbriel da:Umbriel (måne)el:Ουμβριήλ (δορυφόρος)fa:اومبریلgl:Umbriel (lúa)hr:Umbriel (mjesec)

Umbriel, along with another Uranian satellite, Ariel, was discovered by William Lassell on October 24, 1851. Umbriel [UM-bree-ul] is the darkest satellite of Uranus. Some polygons correspond to depressions of a few kilometers deep and may have been created during an early episode of tectonic activity.  Mean distance from Uranus (km)265,970  Numerous valleys and It is probably the floor of a crater. [25] In fact, among the Uranian moons only Oberon has more impact craters than Umbriel. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. monoxide.

 Visual geometric albedo0.18  Since the closest distance between Voyager 2 and Umbriel was 325,000 km (202,000 mi),[37] the best images of this moon have a spatial resolution of about 5.2 km.

However, the presence of the bright feature within Wunda seems to contradict this hypothesis. the fluorescent cheerio. Its density has been calculated at being 1.459. [13] Umbriel is the "dusky melancholy sprite" in Alexander Pope's The Rape of the Lock,[14] and the name suggests the Latin umbra, meaning shadow. [17][18], Currently Umbriel is not involved in any orbital resonance with other Uranian satellites.

The fluid could not have been water

lower in elevation.

A massive star evolves in... Chitosan, sodium alginate, dextran and gelatin are hydrophilic biodegradable polymers which may be used for the preparation of nanopar... NEARLY THE SAME SIZE AS MERCURY , Callisto is the third largest moon in the Solar System .