I have always been impressed by how smooth the rings of Saturn look like. But the rings are actually made up of small chunks of ice, and sharp-eyed users at the Unmanned Spaceflight.com forum noticed that thousands of small boulders and moonlets were casting shadows on the ring, reminding us that the ring is not just one huge solid thing. It helps that the Sun is now lower on the horizon from the viewpoint of the rings, which means that longer shadows are cast.
