Enceladus is a small, brilliantly white moon of Saturn that sprays jets of water from an ocean beneath its south pole, out into space and into Saturn’s rings.
At a glance
| radius | 252 km (0.0396 × Earth) |
|---|---|
| distance from its planet | 238,000 km |
| one orbit | 1.37 days |
| reflects | 99% of the sunlight it gets |
Read off the piece’s own catalogue, the same values it draws with.
About Enceladus
Enceladus is small even among moons, yet it is the most reflective body in the Solar System, its surface coated with fresh ice and snow. Some regions are cratered and old, while others are smooth and young, and near the south pole run four long fractures known as the tiger stripes, warmer than the ice around them.
The Cassini spacecraft discovered plumes of water vapour and ice grains erupting from those fractures and flew through them. It found salts, silica, organic molecules and hydrogen in the spray, evidence of a global salty ocean under the ice in contact with a warm rocky core, perhaps at hydrothermal vents. The ice grains escape the moon’s weak gravity and feed Saturn’s broad, faint E ring.
The energy comes from tides: Enceladus is held in an orbital rhythm with the larger moon Dione that keeps Saturn’s gravity flexing it. Few places beyond Earth combine liquid water, chemistry and energy so accessibly.
What you see in the piece
Enceladus reflects almost all the sunlight that reaches it, so although it is tiny it appears very bright when you fly close to Saturn. From any distance beyond the planet it is lost, and from another star it cannot be seen at all.
Questions
Why is Enceladus so bright?
Its surface is covered in fresh ice and snow, partly fallen back from its own plumes, so it reflects 99% of the sunlight it gets.
Does Enceladus have an ocean?
Yes. Cassini flew through the plumes erupting from its south pole and found salty water, silica and organic molecules, showing a global ocean beneath the ice.