Geysers on Enceladus appear to be driven by Saturn’s gravity

BBC : In 2005, photos of Saturn’s moon Enceladus revealed massive geysers at the moon’s southern pole. Further observation showed that the geysers spew from a series of active fissures in Enceladus’s icy crust, but what drove the geological activity was unclear. Now, Matthew Hedman of Cornell University and his colleagues believe they’ve found a major connection between the geysers and Saturn’s gravitational influence. They examined 252 pictures taken by Cassini of Enceladus orbiting Saturn, and controlled for factors that affect brightness. They found that the geysers’ plumes were four times brighter when Enceladus was farthest from Saturn than when it was closest. Their findings matched models that predicted the fissures would be opened widest at that distant point and thus would allow the larger discharge. The research may also help to determine whether Enceladus has a liquid ocean underneath its frozen surface.