Bright moon of UranusCanyons on a bright ice world

Ariel

Ariel is the brightest of Uranus's major moons, with broad valleys and tectonic scars across its surface.

Moon of Uranus · 1,158 km across · 2.52-day orbit · brightest Uranian major moon

Host: Uranus
Type: Icy moon
Mean diameter: 1,158 km
Mean orbital radius: 190,900 km
Orbital period: 2.52 days
Surface gravity: 0.269 m/s²
Surface: Bright ice and faulted terrain
Discovered: 1851 · William Lassell

Ariel up close

NASA imagery

Voyager 2 image of Uranus's bright moon Ariel at closest approach — **Ariel at closest approach** Voyager 2 captured Ariel's bright, fractured surface during its 1986 flyby. Long valleys cut across ancient cratered terrain. Image: NASA/JPL.

The brightest Uranian moon

Ariel reflects more light than Uranus's other large moons. Its surface includes extensive networks of valleys, ridges and chasms, some of which cut through older impact terrain.

The relative scarcity of large craters in the youngest regions suggests that geological activity resurfaced parts of Ariel after the heaviest period of impacts.

A history of stretching

Tidal heating, changes in the moon's orbit, or an ancient subsurface ocean may have driven the tectonic deformation. Whether any liquid remains today is unknown.

Voyager 2 saw only one hemisphere at useful resolution. A return mission to Uranus would reveal whether Ariel's canyon networks are still changing.

Worth knowing

Ariel is named after a spirit in Shakespeare's The Tempest.
It is the brightest of Uranus's five major moons.
Voyager 2 imaged only about 35% of Ariel's surface at useful resolution.

Watch and explore

Research & further reading

Mission imagery and measurements are interpreted alongside orbital data. Follow the source links for the current NASA overview and precise satellite parameters.

Mission reference NASA · Ariel ↗ NASA's overview of Ariel and its exploration. Orbital data NASA/JPL satellite elements ↗ Mean orbital elements and current satellite catalogue data.