Astronomers have detected a huge plume of water vapour spurting out into space from Enceladus, an icy moon of Saturn.
The 504km-wide (313 miles) moon is well known for its geysers, but this is a particularly big one.
The water stream spans some 9,600km – a distance equivalent to that of flying from the UK to Japan.
Scientists are fascinated by Enceladus because its sub-surface salty ocean – the source of the water – could hold the basic conditions to support life.
Nasa’s Cassini mission (2004-2017) gathered tantalising evidence of the necessary chemistry by regularly flying through the geysers and sampling the water with its instruments – although it made no direct detection of biology.
The new super-plume was spied by the James Webb Space Telescope. Previous observations had tracked vapour emissions extending for hundreds of kilometres, but this geyser is on a different scale.
The European Space Agency (Esa) calculated the rate at which the water was gushing out at about 300 litres per second. This would be sufficient to fill an Olympic-sized swimming pool in just a few hours, Esa said.
Webb was able to map the plume’s properties using its extremely sensitive Near-Infrared Spectrograph (NIRSpec) instrument.
The instrument showed how much of the ejected vapour (about 30%) feeds a fuzzy torus of water co-located with one of Saturn’s famous rings – its so-called E-ring.