Ariel

The Youngest Looking

The brightest Uranian moon with evidence of recent geological activity and smooth plains

Orbital Period

2.52 days

Tidal Locking

Yes

Same face always visible

Planet Rotations

3.5×

per orbit

Atmosphere

🌙 Mind-Blowing Fact

Ariel is the brightest and youngest-looking Uranian moon! Large parts of its surface are smooth and crater-free, suggesting geological activity erased old craters within the last billion years!

What is Time on Ariel?

Ariel is Uranus's fourth-largest moon and its brightest. Unlike ancient Oberon, Ariel shows signs of relatively recent geological activity.

The 2.5-Day Orbit

One orbit = 2.52 Earth days - Quick rounds!
Closest major moon to Uranus
Uranus fills 10° of sky - Huge sideways planet view
Fast orbit - See Uranus rotate 3.5 times

The Young Surface

Ariel's surface is geologically young:

Large smooth plains with few craters
Evidence of past geological activity
Possibly active within last billion years
Contrast with ancient Oberon

The Great Canyons

Ariel features extensive canyon systems:

Valleys up to 10 km deep!
Longer and deeper than Miranda's
Filled with smooth material (cryovolcanic?)
Evidence of expansion and resurfacing

The Bright Appearance

Ariel is the brightest Uranian moon:

Fresh, clean water ice
Less radiation darkening
Young surface not yet weathered
Reflects more light than siblings

Time and Geological Activity

Ariel's youth suggests:

Active or recently active interior
Possible tidal heating (4:1 resonance with Miranda)
Subsurface ocean? (speculative)
Time has been kinder to Ariel than Oberon

A Day in the Life

The Fresh Face

You stand in one of Ariel's great canyons, looking up at 10-kilometer-high walls of ice. The walls are smooth - unnaturally smooth compared to Oberon's ancient, cratered surface.

"This canyon formed within the last billion years," your guide explains. "Maybe less. The floor is smooth because it was filled with cryovolcanic flows - liquid water mixed with ammonia, erupting from Ariel's interior and freezing in the canyon."

You touch the smooth canyon floor. Less than a billion years old. On Oberon, such smoothness would be impossible - 4 billion years of impacts have cratered everything. But here on Ariel, time has been reset.

"Why is Ariel so young?" you ask.

"Tidal heating, possibly," the guide replies. "Ariel is in resonance with Miranda. The gravitational interactions heat Ariel's interior. That heat drives geological activity. Activity that erases old craters. That creates new canyons. That keeps Ariel young."

You look up at Uranus, spinning sideways, filling 10 degrees of sky. In 2.52 days, you'll complete an orbit. Uranus will rotate 3.5 times. And Ariel? Ariel will remain young - at least in geological terms - for perhaps another billion years before tidal heating fades and time begins to scar its surface like it has scarred Oberon's.

"Age is relative on Uranian moons," you say.

"Ariel proves it," the guide agrees. "Some moons remember everything. Ariel... Ariel chose to forget."

Thought Experiments

Why does Ariel look so much younger than Oberon?

Ariel has been geologically active more recently! Tidal heating from its orbital resonance with Miranda probably kept Ariel's interior warm enough to drive geological activity - cryovolcanism, tectonic movement, resurfacing. This activity erased old craters and created smooth plains. Oberon, farther out and without significant resonances, went geologically dead billions of years ago and preserved its ancient surface.

Could there be liquid water under Ariel's surface?

It's possible! If tidal heating is still active, Ariel might maintain a subsurface ocean of water mixed with ammonia (which lowers the freezing point). This is speculative, but the evidence of recent geological activity suggests Ariel's interior might still be warm. Future missions could look for signs of current activity - maybe plumes like Enceladus!