The geyser of ice and water vapour erupting from the south pole of Enceladus, a tiny moon of Saturn, contains complex organic molecules, NASA scientists have discovered.

The Cassini spacecraft flew through the plume on 12 March and got its first good taste of the jet's chemistry — which is unexpectedly similar to that of a comet.

The flyby results, reported on 26 March, also include thermal images of the four long cracks from which the plume emanates. At their hottest, the cracks were 93 °C warmer than the rest of the moon, indicating underground reservoirs of liquid water. This all suggests that Enceladus formed differently from, and probably later than, the rest of the Saturn system.