Observing Saturn, Herschel has detected evidence of water molecules in a huge torus surrounding the planet and centred on the orbit of its small moon, Enceladus. The water plumes on Enceladus, which were detected by the Cassini-Huygens mission, inject the water into the torus and part of it eventually precipitates into Saturn's atmosphere. The new study has identified Enceladus as the primary water supply to Saturn's upper atmosphere; this is the first example in the Solar System of a moon directly influencing the atmosphere of its host planet.
Water plumes emanating from Saturn's moon Enceladus as observed by Cassini - NASA/JPL/Space Science Institute
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