Ariel (moon)

Ariel
The dark face of Ariel, cut by valleys and marked by craters, appears half in sunlight and half in shadow
Ariel in greyscale as imaged by Voyager 2 in 1986. Extensive grabens are visible, including the Kachina Chasmata in the upper part of the image.
Discovery
Discovered byWilliam Lassell
Discovery date24 October 1851
Designations
Designation
Uranus I
Pronunciation/ˈɛəriəl/ or /ˈæriəl/[1]
AdjectivesArielian /æriˈliən/[2]
Orbital characteristics[3]
190900 km
Eccentricity0.0012
2.520 d
5.51 km/s[a]
Inclination0.260° (to Uranus's equator)
Satellite ofUranus
Physical characteristics
Dimensions1162.2 × 1155.8 × 1155.4 km[4]
Mean radius
578.9±0.6 km (0.0908 Earths)[4]
4211300 km2[b]
Volume812600000 km3[c]
Mass(1.2331±0.0180)×1021 kg[6]
Mean density
1.517 g/cm3 (calculated)
0.246 m/s2[d]
0.533 km/s[e]
synchronous
Albedo
  • 0.53 (geometrical)
  • 0.23 (Bond)[7]
Surface temp. min mean max
solstice[8][9] ? ≈ 60 K 84 ± 1 K
14.8 (R-band)[10]

Ariel is the fourth-largest moon 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.

After Miranda, Ariel is the second-closest of Uranus's five major rounded satellites. Among the smallest of the Solar System's 20 known spherical moons (it ranks 14th among them in diameter), it is believed to be composed of roughly equal parts ice and rocky material. Its mass is approximately equal in magnitude to Earth's hydrosphere.

Like all of Uranus's moons, Ariel probably formed from an accretion disc that surrounded the planet shortly after its formation, and, like other large moons, it is likely differentiated, with an inner core of rock surrounded by a mantle of ice. Ariel has a complex surface consisting of extensive cratered terrain cross-cut by a system of scarps, canyons, and ridges. The surface shows signs of more recent geological activity than other Uranian moons, most likely due to tidal heating.

  1. ^ "Ariel". Merriam-Webster.com Dictionary.
  2. ^ DeKoven (1991) Rich and strange: gender, history, modernism
  3. ^ Cite error: The named reference orbit was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Thomas 1988 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference French et al. 2024 was invoked but never defined (see the help page).
  6. ^ Jacobson (2023), as cited in French et al. (2024)[5]
  7. ^ Cite error: The named reference Karkoschka 2001, Hubble was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Grundy Young et al. 2006 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Hanel Conrath et al. 1986 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Arlot Sicardy 2008 was invoked but never defined (see the help page).


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