major moon · moon of Saturn
Dione
An icy moon of Saturn streaked with bright ice cliffs, which may hide a thin ocean deep below its surface.
- Distance from Earth today
- 1.28 billion km8.556 AU · light: 1 h 11 min
- Distance from the Sun today
- 1.41 billion km9.425 AU
- As of
- 2 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
- 1,123 km
- Mass
- 1,095 × 10¹⁸ kg
- Density
- 1,478 kg/m³
- Mean distance from the planet
- 377,700 km
- Orbital period
- 2.74 days
- Orbital eccentricity
- 0.0020
- Orbital inclination
- 0.0°
Source of the figures: JPL SSD – Planetary Satellites (public domain).
Discovery: 1684 – Giovanni Domenico Cassini
Description
Dione is a mid-sized icy moon of Saturn, discovered by Giovanni Domenico Cassini in 1684. Its trailing hemisphere is covered with bright, wispy streaks that the Cassini spacecraft revealed to be networks of ice cliffs and fractures created by tectonic stresses. Gravity data from Cassini suggest that a layer of liquid water may lie deep beneath its crust. Dione shares its orbit with two small Trojan moons, Helene and Polydeuces. It was imaged by both Voyagers and later studied closely by Cassini.