Oberon

The Ancient Survivor

Uranus's outermost major moon, heavily cratered with a mysterious dark surface

Orbital Period

13.46 days

Tidal Locking

Yes

Same face always visible

Planet Rotations

18.8×

per orbit

Atmosphere

🌙 Mind-Blowing Fact

Oberon is the most heavily cratered moon of Uranus, with some craters over 4 billion years old! It also has mysterious dark material on its surface - possibly carbon-rich organic compounds created over billions of years!

What is Time on Oberon?

Oberon is the outermost major moon of Uranus, a dark, ancient world covered in impact craters that have survived for billions of years.

The 13.5-Day Orbit

One orbit = 13.46 Earth days - Nearly two weeks
Most distant Uranian major moon
Uranus appears smaller - 3.3 degrees
Ancient, unchanged surface - Oldest in Uranus system

The Dark Surface

Oberon is notably darker than other Uranian moons:

Covered in dark deposits (possibly carbon-rich)
May be from impacts or UV radiation
Creates a reddish-dark appearance
Oldest surface shows most radiation damage

The Giant Mountain

Oberon has a mysterious 6km-high mountain:

Taller than Denali!
Possibly a central peak of a buried crater
Or result of ancient tectonics
One of the few major features on Oberon

The 42-Year Polar Night

Like all Uranian moons:

42 years of sunlight at poles
42 years of darkness at poles
Currently in northern summer (since 1986)
Polar night coming to north pole in 2028

A Day in the Life

The Oldest Scars

You land on Oberon's heavily cratered surface. The ground is dark - darker than any other Uranian moon. Every direction you look, craters upon craters.

"Some of these impacts are 4 billion years old," your geologist companion says, scanning the surface. "Oberon was bombarded early in solar system history and... never resurfaced. These scars have been here for 4 billion years."

You look at a crater to your left - perhaps 20 kilometers across. That impact happened when Earth was barely formed. When life on Earth was just beginning. And here it sits, unchanged, a permanent scar on Oberon's ancient face.

"On Enceladus, the surface is renewed," the geologist continues. "On Europa, it's young. But Oberon? Oberon is OLD. These craters are TIME CAPSULES. They've seen 4 billion years of solar system history. They've orbited Uranus 100 billion times. They've experienced 50 million 42-year polar nights."

You look up at Uranus, spinning sideways, smaller from this distant orbit. Oberon completes an orbit every 13.5 days. Uranus rotates 19 times during that orbit. And these craters? These craters have been here through it all.

"Time moves differently on ancient worlds," you say.

"Time moves the same," the geologist replies. "But Oberon remembers ALL of it. Nothing erases the past here. Every impact, every orbit, every moment - preserved forever in these craters."

You touch the dark, ancient surface. 4 billion years old. Beneath your gloved hand.

Thought Experiments

Why is Oberon so heavily cratered compared to other Uranian moons?

Oberon has had NO geological resurfacing in billions of years. While moons like Ariel and Miranda show evidence of past activity that erased old craters, Oberon has been geologically dead for most of its history. Every impact that ever hit it is still visible. It's a complete record of 4 billion years of bombardment.

What is the dark material on Oberon's surface?

Likely a combination of carbon-rich organic compounds created by billions of years of UV radiation hitting surface ice, mixed with dark material from impacts. Over 4 billion years, this "space weathering" has darkened Oberon more than any other Uranian moon. The dark material is literally the result of time - radiation slowly transforming the surface over eons.