This picture of Saturn's icy moon Enceladus just came down from the spacecraft yesterday, and is very cool:
[Click to engeysernate.] First, this is a raw image, which means there has been no processing on it. It's uncalibrated and uncleaned, straight from the spacecraft. So some of the bright specks in it are not real, but probably things like cosmic ray hits on the detector. But what a picture! Enceladus has a string of water geysers erupting from its south pole region, and usually they are seen individually. But this view shows them all blending together, as if a sheet of ice is spraying out of the tiny moon! Even cooler, look just above the limb of the moon to the left: I can't be totally positive, but I think that grayish crescent is the shadow of the moon falling across the spray! The angle looks right; from the thin brightly lit crescent on the right (the part of the moon we can see that's in direct sunlight), you can tell the spacecraft is looking nearly straight down on the dark side of the moon (the faintly lit right half of the moon is probably due to reflected light from Saturn itself). The Sun is lighting up the plumes, and the shadow of the moon's edge would fall pretty much where we're seeing it. If so, well, wow! Very pretty. Well, it's pretty anyway, but a big part of my brain goes ping! when I understand what I'm seeing in these pictures. That's not as often as I'd like -- Saturn is really, really weird -- but still, the fact that we can take pictures in situ from a billion kilometers or more away is also enough to make all kinds of regions of my brain light up.
Image credit: NASA/JPL/Space Science Institute. Tip o' the Old Faithful to, as usual, Carolyn Porco.