As I mentioned in a recent blog post, Saturn is currently presenting itself to us with its rings and moon orbits nearly edge-on. I knew this would mean we'd see transits of the moons: from our view, the moons seem to pass directly over the face of Saturn.
|If you look at this still frame from the animation, you can see incredible detail in the rings, and even that the shadow is not quite symmetric; probably a reflection (so to speak) of Epimetheus' irregular shape.|
Some of the other moons are creating these dances as well; here is the even smaller flying-saucer-shaped Pan (just 20 km (12 miles) across) as it orbits in a gap in the rings, casting its own shadow across the rings:
Can you see the moon Pan in the gap in the rings and its shadow? It's tiny in that version, so take a look at this zoom:
Whoa, cool. Pan is actually orbiting in that ring gap, so the rings have to be almost perfectly edge-on to the Sun to get that shadow. Right now that's not quite the case; there's still a bit of a tilt. But as Saturn orbits the Sun that angle will diminish, and in a few months (in August) it'll be precisely 0. Then we'll see the shadows stretching out along the rings, lengthened the same way your own shadow is elongated at sunset. As we approach this point in time -- what's really the Equinox on Saturn, the same as the Equinox we just had on Earth -- well see this more and more, so expect a ton more devastating animations and images from Cassini in the months to come!