Everybody knows about the tiger stripes on Enceladus: the four parallel, long-running ‘sulci’ or cracks from which plumes of ice and gas spew into Saturn’s neighborhood. Now Enceladus has got ‘shark fins’: raised medial ridges, visible within the tiger stripes. That was the term introduced by Paul Helfenstein of Cornell University, who works on Cassini’s main imaging team. “It’s turning into a real zoo here,” he says.

He didn’t have any new pics from the recent flyby on October 9 (the closest yet), but the team is starting to come up with better explanations for the jumble of faults at the Enceladus’ south pole. The shark fins – one of which is the pillowy feature bottom right in the photo – are a feature borrowed from terrestrial geology, when shear and compressive stresses are combined. The oil people call them ‘positive flower structures.’ The space geeks call them ‘shark fins’. Gotta love it. A cartoon explaining the sharks a little more clearly after the jump.