An ocean of water that could support life lies under the surface of Saturn's tiny moon Enceladus, scientists have confirmed.
The ocean is buried beneath 18 to 24 miles (29-39km) of ice and could be larger than the biggest of North America's Great Lakes.
Scientists made the discovery after measuring gravitational anomalies picked up by the American space agency Nasa's Cassini spacecraft, which has spent 10 years studying Saturn and its moons.
In 2005, Cassini sent back astounding images of water vapour jetting from the surface of Enceladus, experts believed a large reservoir of underground water could be fuelling the plumes.
The new findings, reported in the journal Science, confirm that a large water ocean about six miles (10km) deep really does lie beneath the moon's southern polar region.
– Professor David Stevenson, California Institute of Technology
This water ocean... may extend halfway or more towards the equator in every direction.This means that it is as large - or larger - than Lake Superior.
Jupiter's much bigger moon Europa is also known to have liquid water under its surface. Both could be possible habitats for extraterrestrial microbes, scientists believe.
Oceans of water may also be hidden under the surfaces of Saturn's largest moon, Titan, and Jupiter's moon, Callisto.