Like any scientist, I love a good mystery. Sometimes it’s fun when they are long, complicated, involve subtle and difficult layers, and require a vast effort to unravel.
And sometimes it’s cool when they are simply stated and simply solved. Like asking "Where does the water in Saturn’s upper atmosphere come from?" and finding out the answer is "It rains down from the moon Enceladus."
Water has been seen deep in Saturn’s atmosphere before, but a few years back it was detected in the upper atmosphere as well, and that’s a bit weird; there don’t appear to be any ways to get it from deep down in Saturn to the top parts of its clouds. So how did it get there?
Well, the tiny, icy moon Enceladus was discovered to have geysers at its south pole, actively spewing out quite a bit of water into space. Most of it goes into space and is gone forever. Some actually forms a ring around Saturn called the E-ring, and some no doubt hits other moons. Generally, when a moon blasts stuff into space (like Jupiter’s moon Io does with its sulfur ...
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