Ariel New Compact Laundry Powder 10 Wash 650g 90327

Product Information

Both Ariel and the slightly larger Uranian satellite Umbriel were discovered by William Lassell on 24 October 1851. [11] [12] Although William Herschel, who discovered Uranus's two largest moons Titania and Oberon in 1787, claimed to have observed four additional moons, [13] this was never confirmed and those four objects are now thought to be spurious. [14] [15] [16] Surface gravity derived from the mass m, the gravitational constant G and the radius r: G m / r 2 {\displaystyle Gm/r Ariel appears to be fairly evenly cratered compared to other moons of Uranus; [20] the relative paucity of large craters [i] suggests that its surface does not date to the Solar System's formation, which means that Ariel must have been completely resurfaced at some point of its history. [36] Ariel's past geologic activity is believed to have been driven by tidal heating at a time when its orbit was more eccentric than currently. [25] The largest crater observed on Ariel, Yangoor, is only 78km across, [37] and shows signs of subsequent deformation. All large craters on Ariel have flat floors and central peaks, and few of the craters are surrounded by bright ejecta deposits. Many craters are polygonal, indicating that their appearance was influenced by the preexisting crustal structure. In the cratered plains there are a few large (about 100km in diameter) light patches that may be degraded impact craters. If this is the case they would be similar to palimpsests on Jupiter's moon Ganymede. [36] It has been suggested that a circular depression 245km in diameter located at 10°S 30°E is a large, highly degraded impact structure. [42] Origin and evolution [ edit ]

Except for water, the only other compound identified on the surface of Ariel by infrared spectroscopy is carbon dioxide (CO 2), which is concentrated mainly on its trailing hemisphere. Ariel shows the strongest spectroscopic evidence for CO 2 of any Uranian satellite, [8] and was the first Uranian satellite on which this compound was discovered. [8] The origin of the carbon dioxide is not completely clear. It might be produced locally from carbonates or organic materials under the influence of the energetic charged particles coming from Uranus's magnetosphere or solar ultraviolet radiation. 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. Another possible source is the outgassing of primordial CO 2 trapped by water ice in Ariel's interior. The escape of CO 2 from the interior may be related to past geological activity on this moon. [8] The second main terrain type—ridged terrain—comprises bands of ridges and troughs hundreds of kilometers in extent. It bounds the cratered terrain and cuts it into polygons. Within each band, which can be up to 25 to 70km wide, are individual ridges and troughs up to 200km long and between 10 and 35km apart. The bands of ridged terrain often form continuations of canyons, suggesting that they may be a modified form of the graben or the result of a different reaction of the crust to the same extensional stresses, such as brittle failure. [36] False-color map of Ariel. The prominent noncircular crater below and left of center is Yangoor. Part of it was erased during formation of ridged terrain via extensional tectonics. The observed surface of Ariel can be divided into three terrain types: cratered terrain, ridged terrain, and plains. [36] The main surface features are impact craters, canyons, fault scarps, ridges, and troughs. [37] Graben (chasmata) near Ariel's terminator. Their floors are covered by smooth material, possibly extruded from beneath via cryovolcanism. Several are cut by sinuous central grooves, e.g. Sprite and Leprechaun valles above and below the triangular horst near the bottom. The cratered terrain, a rolling surface covered by numerous impact craters and centered on Ariel's south pole, is the moon's oldest and most geographically extensive geological unit. [36] It is intersected by a network of scarps, canyons (graben), and narrow ridges mainly occurring in Ariel's mid-southern latitudes. [36] The canyons, known as chasmata, [38] probably represent graben formed by extensional faulting, which resulted from global tensional stresses caused by the freezing of water (or aqueous ammonia) in the moon's interior (see below). [20] [36] They are 15–50km wide and trend mainly in an east- or northeasterly direction. [36] The floors of many canyons are convex; rising up by 1–2km. [38] Sometimes the floors are separated from the walls of canyons by grooves (troughs) about 1km wide. [38] The widest graben have grooves running along the crests of their convex floors, which are called valles. [20] The longest canyon is Kachina Chasma, at over 620km in length (the feature extends into the hemisphere of Ariel that Voyager 2 did not see illuminated). [37] [39] Because Ariel, like Uranus, orbits the Sun almost on its side relative to its rotation, its northern and southern hemispheres face either directly towards or directly away from the Sun at the solstices. This means it is subject to an extreme seasonal cycle; just as Earth's poles see permanent night or daylight around the solstices, Ariel's poles see permanent night or daylight for half a Uranian year (42 Earth years), with the Sun rising close to the zenith over one of the poles at each solstice. [8] The Voyager 2 flyby coincided with the 1986 southern summer solstice, when nearly the entire northern hemisphere was dark. Once every 42 years, when Uranus has an equinox and its equatorial plane intersects the Earth, mutual occultations of Uranus's moons become possible. A number of such events occurred in 2007–2008, including an occultation of Ariel by Umbriel on 19 August 2007. [23]Ariel is the fourth-largest of the 27 known moons of Uranus. Ariel orbits and rotates in the equatorial plane of Uranus, which is almost perpendicular to the orbit of Uranus and so has an extreme seasonal cycle. It was discovered in October 1851 by William Lassell and named for a character in two different pieces of literature. As of 2019, much of the detailed knowledge of Ariel derives from a single flyby of Uranus performed by the space probe Voyager 2 in 1986, which managed to image around 35% of the moon's surface. There are no active plans at present to return to study the moon in more detail, although various concepts such as a Uranus Orbiter and Probe have been proposed.

The apparent magnitude of Ariel is 14.8; [10] similar to that of Pluto near perihelion. However, while Pluto can be seen through a telescope of 30cm aperture, [46] Ariel, due to its proximity to Uranus's glare, is often not visible to telescopes of 40cm aperture. [47]On 26 July 2006, the Hubble Space Telescope captured a rare transit made by Ariel on Uranus, which cast a shadow that could be seen on the Uranian cloud tops. Such events are rare and only occur around equinoxes, as the moon's orbital plane about Uranus is tilted 98° to Uranus's orbital plane about the Sun. [51] Another transit, in 2008, was recorded by the European Southern Observatory. [52] See also [ edit ]