regular moon · moon of Saturn
Hyperion
A sponge-like, irregular moon of Saturn that tumbles chaotically as it orbits, its surface pitted with deep, sharp-edged craters.
- Distance from Earth today
- 1.28 billion km8.573 AU · light: 1 h 11 min
- Distance from the Sun today
- 1.41 billion km9.425 AU
- As of
- 4 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
- 270 km
- Mass
- 5.55 × 10¹⁸ kg
- Density
- 539 kg/m³
- Mean distance from the planet
- 1,481,500 km
- Orbital period
- 21.3 days
- Orbital eccentricity
- 0.105
- Orbital inclination
- 0.6°
Source of the figures: JPL SSD – Planetary Satellites (public domain).
Discovery: 1848 – William Cranch Bond, George Phillips Bond, William Lassell
Description
Hyperion is one of the largest moons in the Solar System that is not round. It was discovered in 1848 independently by William and George Bond in the United States and by William Lassell in England. Close-up images from Cassini revealed a bizarre, sponge-like surface of deep, sharp-rimmed craters, explained by its very low density: Hyperion is highly porous, so impacts compress material rather than blasting it out. Gravitational interactions with Titan keep its spin chaotic, so it tumbles unpredictably instead of rotating steadily.