Cosmic Scale
Mimas
Moon of Saturn · 1.4 billion km from the Sun
How big is Mimas?
Mimas is about 396 km across.
See Mimas in 3D, at true scale
Mimas is the smallest body in the Solar System still rounded by its own gravity. One enormous impact crater, Herschel, spans a third of its width and gives it an uncanny resemblance to a certain fictional battle station.
At a glance
| Diameter | 396 km |
|---|---|
| Mass | 3.75 × 10¹⁹ kg |
| Diameter compared with Earth | 0.031 × Earth |
| Orbits | Saturn, every 22.6 hours |
| Herschel crater | 130 km across |
| Surface | About −200 °C |
| Discovered | 1789, William Herschel |
Good to know
- The impact that made Herschel nearly shattered the moon; fractures show on the opposite side.
- Measurements published in 2024 suggest a young liquid ocean may lie 20–30 km beneath the ice.
- Mimas is mostly water ice, which is why so small a body is round at all.