Were their any hints that Enceladus could be odd?
We knew Enceladus was strange ever since Voyager flew past in the early 1980s. We knew it had an extremely bright surface – it’s the brightest object in the solar system. The surface is as bright as freshly fallen snow. It has a very strange and complicated geology. The surface has been torn up by internal forces, and there are very few craters. So we knew geological activity had taken place recently. But usually when we say “recently” we are thinking 100 million years ago, not right now. The other interesting thing is that there is a ring of dust or ice particles that surround Saturn right at the orbit of Enceladus. It appeared that debris was coming off Enceladus and feeding into the ring. So we had much circumstantial evidence that something was going on, but I think we were all taken aback to see this very active phenomenon going on under our noses. What is causing the surprising heat? It almost certainly has something to do with tidal heating, which is the mechanism that powers th
