It’s difficult to get a sense of scale when viewing Saturn’s rings, but the Cassini Division (seen here between the bright B ring and dimmer A ring) is almost as wide as the planet Mercury. (See PIA11142 for a labeled panorama of features in the rings.)

The 2,980-mile-wide (4,800-kilometer-wide) division in Saturn’s rings is thought to be caused by the moon Mimas. Particles within the division orbit Saturn almost exactly twice for every time that Mimas orbits, leading to a build-up of gravitational nudges from the moon. These repeated gravitational interactions sculpt the outer edge of the B ring and keep its particles from drifting into the Cassini Division.

(Credit: NASA/JPL-Caltech/Space Science Institute)