astroengine writes "Giant plumes of water vapor and ice particles blast from geysers on Saturn's moon Enceladus — but scientists have often wondered why the relatively diminutive moon, which measures only 310 miles across, wasn't frozen solid. They also began creating computer models to try to unravel the physics behind the stunning geological phenomenon. Now, after analyzing 252 images of Enceladus' plumes, scientists have part of the answer: Gravitational variations during the moon's slightly eccentric, 1.37-day orbit around Saturn create tidal forces that directly impact how much material is shot into space from four fissures around the moon's south pole. 'It's not a subtle variation. You can look at some of the images and you can actually see it with your eyes. It's very dramatic,' said planetary scientist Matthew Hedman."