Ariel (air'-ee-əl, IPA /ˈɛəriəl/) is a moon of Uranus discovered on 24 October 1851 by William Lassell. It was discovered at the same time as Umbriel. Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... BIC pen cap, about 1 gram. ... Gravity is a force of attraction that acts between bodies that have mass. ... Acceleration is the time rate of change of velocity, and at any point on a velocity-time graph, it is given by the slope of the tangent to that point In physics or physical science, acceleration (symbol: a) is defined as the rate of change (or derivative with respect to... Space Shuttle Atlantis launches on mission STS-71 In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... In astronomy, synchronous rotation is a planetological term describing a body orbiting another, where the orbiting body takes as long to rotate on its axis as it does to make one orbit; and therefore always keeps the same hemisphere pointed at the body it is orbiting. ... Axial tilt is an astronomical term regarding the inclination angle of a planets rotational axis in relation to its orbital plane. ... Albedo is a ratio of scattered to incident electromagnetic radiation power. ... Fig. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ... This is a concise version of the International Phonetic Alphabet for English sounds. ... Moons of the Solar System scaled to Earths Moon A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Atmospheric characteristics Atmospheric pressure 120 kPa Hydrogen 83% Helium 15% Methane 1. ... 1851 (MDCCCLI) was a common year starting on Wednesday (see link for calendar) of the Gregorian calendar (or a common year starting on Friday of the 12-day-slower Julian calendar). ... William Lassell (June 18, 1799 – October 5, 1880) was a British astronomer, born in Bolton, Greater Manchester, England. ... Atmospheric pressure 0 kPa Umbriel (um-bree-É™l, IPA ) is a moon of Uranus discovered on 1851-10-24 by William Lassell. ...

Name

Ariel is named after the leading sylph in Alexander Pope's poem Rape of the Lock. It is also the name of the spirit who serves Prospero in Shakespeare's Tempest. Sylph is a faux-mythological creature in the Western tradition. ... Alexander Pope, an English poet best known for his Essay on Criticism and Rape of the Lock Alexander Pope (21 May 1688 – 30 May 1744) is generally regarded as the greatest English poet of the early eighteenth century, best known for his satirical verse and for his translation of Homer. ... The Rape of the Lock is a mock-heroic poem written by Alexander Pope and published in May 1717. ... William Shakespeare—born April 1564; baptised April 26, 1564; died April 23, 1616 (O.S.), May 3, 1616 (N.S.)—has a reputation as the greatest of all writers in English. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

The name "Ariel" and the names of all four satellites of Uranus then known were suggested by John Herschel in 1852 at the request of Lassell ([1]). Lassell had earlier endorsed Herschel's 1847 naming scheme for the seven then-known satellites of Saturn and had named his newly-discovered eighth satellite Hyperion in accordance with Herschel's naming scheme in 1848. John Herschel Sir John Frederick William Herschel (7 March 1792 – 11 May 1871) was an English mathematician and astronomer. ... 1852 was a leap year starting on Thursday (see link for calendar). ... 1847 was a common year starting on Friday (see link for calendar). ... Hyperion (hye-peer-ee-ən, IPA , Greek Ὑπερίων) is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. ... 1848 (MDCCCXLVIII) was a leap year starting on Saturday of the Gregorian calendar. ...

It is also designated Uranus I.

Physical characteristics

See also: List of geological features on Ariel

The first and so far only close-up observations of Ariel were made by the Voyager 2 probe during its 1986 Uranus fly-by. Voyager 2 made its closest approach of Ariel on January 24, 1986 and passed within 127,000 km of the moon.^[1] Because the moon's south pole was pointed towards the Sun, only the southern hemisphere was photographed. This is a list of named geological features on Ariel. ... Trajectory Voyager 2 is an unmanned interplanetary spacecraft. ... It has been suggested that this article or section be merged into Unmanned space mission. ... 1986 (MCMLXXXVI) was a common year starting on Wednesday of the Gregorian calendar. ... January 24 is the 24th day of the year in the Gregorian calendar. ... 1986 (MCMLXXXVI) was a common year starting on Wednesday of the Gregorian calendar. ... For other uses, see Sun (disambiguation). ...

Ariel's composition is roughly 70% ices (water ice, carbon dioxide ice, and possibly methane ices) and 30% silicate rock, and it appears to have regions of fresh frost in places, particularly in the ejecta radiating from young impact craters. The oldest and most extensive geologic unit observed on Ariel by Voyager 2 was a vast area of cratered plains centered near Ariel's south pole. Analysis of craters seen on Ariel's cratered plains suggest most are younger than many of those seen on Titania, Oberon, and Umbriel.^[2] The largest crater observed on Ariel is Yangoor, at only 78 km across, and shows signs of deformation since its formation. Voyager 2 also observed a network of faults, canyons, and icy outflows running along Ariel's mid-southern latitudes, breaking up the cratered plains region. Smooth material and grooves are often seen running down length of Ariel's valley networks, suggested that some canyon floors have been covered in warm ice extruded from Ariel's interior.^[2] Methane is a significant and plentiful fuel which is the principal component of natural gas. ... In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ... A volume of rock or ice of identifiable origin and age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. ... Atmospheric pressure   Titania (ti-taan-ee-É™ or tye-tan-ee-É™) is the largest moon of Uranus. ... Atmospheric pressure 0 kPa Oberon (oe-bur-on) is the outermost of the major moons of the planet Uranus. ... Atmospheric pressure 0 kPa Umbriel (um-bree-É™l, IPA ) is a moon of Uranus discovered on 1851-10-24 by William Lassell. ... Fault in metamorphosed strata near Adelaide, Australia Geologic faults or simply faults are planar rock fractures which show evidence of relative movement. ... Grand Canyon, Arizona A canyon or gorge is a deep valley between cliffs often carved from the Earth by a river. ...

Official names have been given to the following geological feature types on Ariel: World geologic provinces Oceanic crust  0-20 Ma  20-65 Ma  >65 Ma Geologic provinces  Shield  Platform  Orogen  Basin  Large igneous province  Extended crust Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason))[1] is the science and study of the solid matter of a celestial body, its composition...

• Craters
• Chasmata (chasms)
• Valles (valleys)

Tycho crater on Earths moon. ... Chasma (pl. ... Vallis (plural valles) is the Latin word for valley. ...

Trivia

• Only July 26, 2006, the Hubble Space Telescope captured a rare transit made by Ariel across the face of Uranus, during which the satellite casted a shadow that could be seen on the Uranian cloudtops. Such events are rare and only occurs during an equinox, as the planet's axis are tilted 98° to the plane of the Solar System.

July 26 is the 207th day (208th in leap years) of the year in the Gregorian Calendar, with 158 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble for his discovery of galaxies outside the Milky Way and his creation of Hubbles Law, which calculates the rate at which the universe is expanding. ... An equinox is one of two opposite points on the celestial sphere where the celestial equator and ecliptic intersect. ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt containing the dwarf planet Ceres, outermost there is the dwarf planet Pluto (the dwarf planet Eris not shown), and a comet. ...

See also

• List of geological features on Ariel

This is a list of named geological features on Ariel. ...

Notes and references

External links

• William Lassell, Astronomical Journal 2 (1851) 70
• AN, 33 (1852) 257/258
• AN, 34 (1852) 325/326
• Ariel basemap derived from Voyager images
• NASA Archive of publically released Ariel images