The Best Image of Saturn's Moon Daphnis Ever Taken

Phil Plait on The Best Image of Saturn's Moon Daphnis Ever Taken. And It's a Stunner.

That’s the highest-resolution image of Daphnis ever taken; for scale, the flying-saucer-shaped moon is about 8 x 8 x 6 km in size. Measured from sea level, Mount Everest is roughly the same size. You can see some structure to Daphnis; there’s a ridge around its equator that’s probably due to ring particles that have piled up there, and a second ridge at higher latitude. The soft appearance to the moon is probably due to the accumulation of small grains of ice from the rings that have coated it, filling in the craters and other features.

That gap in the rings is real. It’s called the Keeler Gap, and it’s about 30-40 km wide. The width of the gap appears foreshortened because Cassini was just above the ring plane when it took the shot; it’s actually several times wider than the moon is long.

But, oh, those ripples! That, my friends, is the result of gravity. It’s a complicated and intricate dance between moon and rings, but it’s worth learning the moves."