Moons · Space Codex
Dione
A dense ice-and-rock moon whose trailing side is streaked with bright 'wisps', which Cassini revealed as walls of fractured ice hundreds of metres high.
Cratered moon laced with ice cliffs
At a glance
Key points
- Bright 'wisps' are ice cliffs hundreds of metres high
- Locked in a 1:2 resonance with Enceladus
- Shares its orbit with two tiny moons
Surface
Dione's leading hemisphere is heavily cratered; its trailing hemisphere carries bright streaks that Voyager could not resolve. Cassini, flying past from 2005, showed them to be fracture cliffs of clean ice, some several hundred metres high.
Interior
A rocky core makes up about a third of the moon. Its resonance with Enceladus may help keep Enceladus's interior warm.
What we still don't know
Whether Dione retains a thin liquid layer beneath its ice, as some interpretations of Cassini gravity data allow.
Missions
- 1977–
Jupiter 1979, Saturn 1980; interstellar space since 25 Aug 2012.
- 1997–2017
Cassini–Huygens
NASA / ESA / ASICompletedOrbited Saturn 2004–2017 and ended by diving into the planet.
First-hand · our 3D model
How we render it
Dione is a sphere wrapped in a global map built from USGS and NASA spacecraft mosaics.
It is drawn at about 4.4% of Saturn's radius, enlarged from its true 0.96% so it stays visible. It orbits almost exactly in Saturn's equatorial plane, with a 2.74-day period kept in true ratio to its neighbours, and keeps one face towards Saturn.
Moon sizes and orbits are compressed so a whole system fits on screen, but never reordered: each moon is drawn at 0.72 × (true size ratio)^0.6 of its planet, capped so no large moon is drawn bigger than it really is, and orbit distances are log-compressed into a band that clears the planet's rings. Orbital periods keep their true ratios, every moon is tidally locked, and on lighter devices only the two largest moons of each planet are drawn.
Related entries
Sources
- JPL Solar System Dynamics: satellite physical parameters (opens in a new tab)
- JPL Solar System Dynamics: satellite mean orbital elements (opens in a new tab)
- NASA NSSDC Saturnian Satellite Fact Sheet (opens in a new tab)
- NASA Science: Dione (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.