major moon · moon of Saturn
Mimas
A small icy moon of Saturn whose giant Herschel crater gives it an uncanny resemblance to the Death Star.
- Distance from Earth today
- 1.28 billion km8.564 AU · light: 1 h 11 min
- Distance from the Sun today
- 1.41 billion km9.425 AU
- As of
- 3 November 2026position from NASA/JPL orbital elements
Where it is today
Top view of the plane of Earth’s orbit, compressed distance scale. Open on the big map with the time slider →
Facts
- Diameter
- 396 km
- Mass
- 37.5 × 10¹⁸ kg
- Density
- 1,150 kg/m³
- Mean distance from the planet
- 186,000 km
- Orbital period
- 22.6 h
- Orbital eccentricity
- 0.020
- Orbital inclination
- 1.6°
Source of the figures: JPL SSD – Planetary Satellites (public domain).
Discovery: 1789 – William Herschel
Description
Mimas is the smallest and innermost of Saturn's major moons, discovered by William Herschel in 1789. It is dominated by the crater Herschel, so large compared with the moon that the impact that made it came close to shattering Mimas entirely; the resemblance to the Death Star from Star Wars is famous. Its gravitational resonance shapes the Cassini Division, the wide gap in Saturn's rings. For a long time it looked like a dead, frozen world, but analysis of tiny wobbles in its rotation and orbit measured by Cassini suggests that a young ocean may lie hidden beneath its cratered crust.