Space · Moons
Ariel
A moon of Uranus — The brightest of Uranus's major moons — rift valleys and resurfaced terrain suggest a more recent geological history.
Quick facts
Parent planet
Diameter (mean)
1158 km
Mass
1.25 × 10²¹ kg
0.017 Moon masses
Mean orbital radius
191,020 km
Orbital period
2.52 Earth days
Discovery year
1851
Discoverer
William Lassell
Naming origin
Sylph in The Rape of the Lock; sprite in The Tempest
Surface conditions
Ariel is the brightest of Uranus's moons (albedo 0.39), with a complex surface of grooved terrain, rift valleys, and ridged plains — evidence of past tectonic activity and possibly cryovolcanism. The youngest-looking surface in the Uranian system; the lack of large craters in some regions suggests resurfacing as recent as 100 million years ago.
Missions and observations
Every Uranus-system mission has had an opportunity to image or characterize Ariel. The list below is the Uranus-system mission catalog; specific Ariel encounters are documented in mission archives.
| Mission | Year at Uranus | Status |
|---|---|---|
|
Voyager 2 NASA |
1986 | Completed |
Naming etymology
Ariel appears as a sylph in Pope's The Rape of the Lock and as a sprite of the air in Shakespeare's The Tempest. Named by John Herschel in 1852.
Methodology & sources
Diameter, mass, and orbital parameters from JPL Solar System Dynamics — Physical Parameters. Discovery year and discoverer from the JPL Satellite Discovery Circumstances. Naming etymology from the IAU Working Group for Planetary System Nomenclature. Agent-matched moon pages use the matching Mungomash team avatar in the hero; non-agent moons are text-only.