The Cassini Division is a prominent gap located between Saturn's A and B rings. It was discovered in 1675 by Giovanni Cassini, an Italian astronomer. The division is about 4,800 kilometers wide and is not completely empty but contains less material compared to the surrounding rings. The gap is caused by gravitational interactions, particularly with Saturn's moon Mimas, which orbits at a distance that resonates with the orbits of particles in the Cassini Division. This gravitational resonance causes particles to be cleared from this region, creating the noticeable gap seen in observations of Saturn's rings.