Moons · Space Codex
Ariel
The brightest of Uranus's large moons, crossed by long fault valleys.
Uranus's youngest, brightest face
At a glance
Key points
It shows the most recent geological activity of the group.
- Brightest of Uranus's five major moons
- Youngest surface of the group
- Named after a spirit in Shakespeare's The Tempest
Surface
Ariel has few large craters and many small ones, so its surface was renewed relatively recently. Fault-bounded valleys run across it, some with smooth floors that may have been flooded by icy material from below.
Exploration
Voyager 2 is the only spacecraft to have visited, passing on 24 January 1986. Uranus was near solstice, so only the southern hemispheres of its moons were in sunlight; the northern halves have never been seen up close.
What we still don't know
What heated Ariel enough to resurface it. Tidal interaction with Uranus in an earlier, more eccentric orbit is one proposal.
Missions
- 1977–
The only spacecraft to visit Uranus (1986) and Neptune (1989); interstellar since 5 Nov 2018.
- 2021–
Infrared observatory at Sun–Earth L2, about 1.5 million km from Earth.
First-hand · our 3D model
How we render it
Ariel is a sphere wrapped in a global map built from USGS and NASA spacecraft mosaics. Voyager 2 imaged only one hemisphere, so the unseen side is a feathered procedural fill.
It is drawn at about 7.5% of Uranus's radius, enlarged from its true 2.3% so it stays visible. It orbits almost exactly in Uranus's equatorial plane, with a 2.52-day period kept in true ratio to its neighbours, and keeps one face towards Uranus.
Moon sizes and orbits are compressed so a whole system fits on screen, but never reordered: each moon is drawn at 0.72 × (true size ratio)^0.6 of its planet, capped so no large moon is drawn bigger than it really is, and orbit distances are log-compressed into a band that clears the planet's rings. Orbital periods keep their true ratios, every moon is tidally locked, and on lighter devices only the two largest moons of each planet are drawn.
Related entries
- UranusIce giant tipped on its side
Sources
- JPL Solar System Dynamics: satellite physical parameters (opens in a new tab)
- JPL Solar System Dynamics: satellite mean orbital elements (opens in a new tab)
- NASA NSSDC Uranian Satellite Fact Sheet (opens in a new tab)
- NASA Science: Ariel (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.