Enceladus

Moon· orbits Saturn

Enceladus is a small, brilliant-white moon of Saturn that jets plumes of water vapour and ice from a subsurface ocean through 'tiger stripe' fractures at its south pole, feeding Saturn's E ring.

Open in 3D viewSee Enceladus in the live, interactive 3D map

Key facts

Mass

1.08 × 10²⁰ kg

0.00147 Moon masses

Radius

252 km

15% of our Moon's radius

Surface gravity

0.113 m/s²

1% of Earth's gravity

Day length

32.89 hours

Orbit around Saturn

1.37 Earth days

Science

Physical

Mass: 1.08 × 10²⁰ kg · 0.00147 Moon masses; JPL / IAU mean radii; spacecraft-tracked GM where measured
Radius: 252 km · 15% of our Moon's radius; JPL / IAU mean radii; spacecraft-tracked GM where measured
Density: 1,610 kg/m³ · 1.6× water; Computed from mass and radius
Surface gravity: 0.113 m/s² · 1% of Earth's gravity; Computed from mass and radius
Escape velocity: 239 m/s · 2% of Earth's escape velocity; Computed from mass and radius

Orbit around Saturn

Distance from Saturn: 238,400 km; From JPL orbital elements
Orbital period: 32.89 hours; From JPL orbital elements
Eccentricity: 0.005; From JPL orbital elements
Inclination to Saturn's Laplace plane: 0.00 °; From JPL orbital elements · The Laplace plane is the one a moon's orbit precesses about: close in it is the planet's equatorial plane, the plane of the rings, and further out it tilts toward the planet's own orbit.

Rotation

Rotation period: 32.89 hours
Tidal locking: Tidally locked to its parent

Temperature

Mean: 75 K (-198 °C)

Composition

Bulk composition: A water-ice surface over a global subsurface ocean and a rocky core; its plumes carry water vapour, salts and organic molecules.

Radiation & temperature

Insolation: 0.0112 S⊕ · 1% of the sunlight Earth receives; Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
Bond albedo: 0.81 · reflects 81% of incoming sunlight; Among the most reflective bodies in the Solar System (Bond albedo ≈ 0.8).
Equilibrium temperature: 60 K (-213 °C); Computed from albedo + distance from the Sun (airless black body)
Measured mean temperature: 75 K (-198 °C)
Greenhouse warming: +15 K; Measured temperature minus the airless equilibrium — the greenhouse effect

Discovery & history

Discovered: August 28, 1789
By: William Herschel
Method: Visual discovery (telescopic)
Name: Enceladus, one of the Giants of Greek myth.

Herschel found the brilliantly white Enceladus in 1789. It stunned scientists when the Cassini orbiter revealed towering geysers of water vapour and ice jetting from 'tiger-stripe' fractures at its south pole — venting from a global subsurface ocean, making it a prime place to search for life.