Ariel (moon)
fourth-largest moon of Uranus
Ariel is the fourth-largest moon of Uranus. Ariel orbits and rotates in Uranus's equatorial plane, which is almost perpendicular to the planet's orbit, giving the moon an extreme seasonal cycle.
It was discovered on 24 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 19 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, grabens and ridges.
The public source identifies “Ariel (moon)” as fourth-largest moon of Uranus. This brief keeps that definition visible, then builds a research path around Ariel, moon and fourth-largest.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 14, 2026. The linked authority identifier is Q3343. The Library of Congress control number is sh94005239. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1851, 2019 and 1986.
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This entry incorporates text from “Ariel (moon)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.