Enceladus

The icy moon that sprays water into space

Enceladus is a small, snow-white, shiny moon — the whitest body in the Solar System. Near its south pole are cracks that shoot fountains of water into space — more than a hundred of them! The water comes from a warm ocean under the ice. These fountains create one of Saturn's rings. Maybe tiny creatures live in that ocean.

Enceladus (radius 252 km, about the size of Britain) orbits Saturn every 1.37 days. Its surface is pure water ice, reflecting 99% of sunlight. Through the 'tiger stripes' (four cracks) near the south pole, more than 100 geysers spray 200 kg of water vapour and ice per second — discovered by Cassini in 2005; in 2015 it flew through the plumes and analysed them: water, salt, organic molecules, hydrogen. This points to a salty ocean beneath 30–40 km of ice, with hydrothermal vents on the seafloor — all the ingredients for life. The plumes feed Saturn's E ring. Enceladus is one of astrobiology's top targets.

Fun facts

• Enceladus is the whitest body in the Solar System — whiter than fresh snow.
• Its geysers create an entire ring of Saturn (the E ring).
• On Enceladus you'd weigh 90 times less than on Earth.