Click flag. Saturn's innermost rings orbit faster than the outer rings. Moon Mimas orbits at twice the speed of a middle region of the rings (orbital resonance). This exerts a regular pull on the particles in that region, clearing it out. This results in the gap in the rings (shown as a thin black circle), called the Cassini gap.
Rings, Saturn, Mimas, and speeds are not to scale. Mimas drawn by Kathy Keane. Model by Chris Keane. See this same model but where we have Mimas rotate sideways around Saturn.
