Saturn is a cool planet. It has rings, over 60 moons and is made of gasses - this always amazed me from even a young age - I remember reading 'The Magic School Bus Explores the Solar System' and then playing the computer game on my fathers computer. The rings in particular really captivated me... But we're getting a little off topic here, lets get a little more into the shot itself.
But just before we do that, this shot is actually somewhat accurate to how astrophysicists believe the rings may look. The shot takes place at the innermost 'D' ring of Saturn, which is the least dense ring.
So, this shot was to set the scene of Saturn, the next shot was fairly static so some movement here was necessary, so the rings felt like a good way to achieve this. The rings were made of many standard geometric shapes (cubes, spheres, pyramids) which were randomised in scale and vertex position, and then displaced via a displacement texture. These objects were then cloned, randomised, and had dynamics applied to them. This cause a lot of playback issues, but by separating each set of rocks (of which there were 10) into separate scene-files, I was able to work efficiently and get near real-time playback. I also rendered them seperately with depth passes as this left me more flexibility in post. Here is the C4D scene with all the ring ice (yes, they're made of ice, not rocks!) merged into one file.