Ariel (moon) - Definition and Overview

Ariel

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Discovery
Discovered by	William Lassell
Discovered in	1851
Orbital characteristics
Mean radius	190,900 km
Perihelion
Aphelion
Eccentricity
Orbital period	2.52 days
Inclination	°
Satellite of	Uranus
Physical characteristics
Mean diameter	1157.8 km
Surface area	4,200,000 km2
Mass	1.35×1021kg
Mean density	1.67 g/cm3
Surface gravity	m/s2
Escape velocity	km/s
Rotation period	2.52 days
Axial tilt	°
Albedo
Surface temperature	min mean max K K K
Atmospheric pressure	0 kPa

Ariel ("AIR ee el") is a moon of Uranus discovered in 1851 by William Lassell. Ariel is named after the leading sylph in Alexander Pope's poem Rape of the Lock. It was discovered at the same time as Umbriel.

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] (http://adsabs.harvard.edu//full/seri/AN.../0034//0000169.000.html)). 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.

Physical characteristics

The first close-up observations of Ariel were made by the space probe Voyager 2 during its January 1986 Uranus fly-by.

Ariel's composition is roughly 50% water ice, 30% silicate rock, and 20% methane ice, and it appears to have regions of fresh frost in places. Largely devoid of impact craters, Ariel appears to have undergone a period of intense geological activity that has produced a huge network of fault canyons and liquid water outflows over its surface.

Scientists recognise the following geological features on Ariel:

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

See: List of geological features on Ariel

External links

• William Lassell, Astronomical Journal 2 (1851) 70 (http://adsabs.harvard.edu//full/seri/AJ.../0002//0000070.000.html)
• AN, 33 (1852) 257/258 (http://adsabs.harvard.edu//full/seri/AN.../0033//0000136.000.html)
• AN, 34 (1852) 325/326 (http://adsabs.harvard.edu//full/seri/AN.../0034//0000169.000.html)