Ariel

The brightest and seemingly youngest of Uranus's major moons — crossed by a network of rift valleys.

Orbits Uranus

Highest albedo of any Uranian moon u2014 appears bright and young.
Extensive system of rift canyons and graben floors resurfaced by possible cryovolcanism.
Mixed water-ice and rocky composition.

About Ariel

Ariel is the fourth-largest moon of Uranus and has the brightest surface of the Uranian moons, suggesting a relatively young crust. Voyager 2 imagery revealed an extensive network of deep rift valleys and smooth “graben floors” inside canyon systems — strong evidence of geologic activity, possibly cryovolcanic resurfacing, early in Ariel’s history.

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Physical Properties

Mean radius579 km

Mass1.251e21 kg

Density1.592 g/cm³

Surface gravity0.249 m/s²

Rotation period60.48 h

Bond albedo0.53

Mean temp60 K

Orbit

OrbitsUranus

Semi-major axis191,020 km

Eccentricity0.0012

Inclination0.041°

Orbital period2.52 d

Gallery

Hand-picked mission imagery of Ariel sourced from NASA and partner archives. Click any photo for full resolution and source attribution.

Uranus's moon Ariel and its fault valleys, from Voyager 2. NASA/JPL-Caltech · Public Domain u2014 NASA Media Usage Guidelines

Branching valleys across the surface of Ariel. NASA/JPL-Caltech

Imagery on this page is provided by the original mission teams. Full attribution terms: Image Rights & Credits.

Sources & Further Reading

Numerical values (radius, mass, orbital elements, temperatures) are drawn from NASA NSSDC Planetary Fact Sheets, JPL Horizons, and the JPL Small-Body Database. Last refreshed: 2026-06-08 01:37:02.