Galileo was the first to detect a disc around Saturn. This was done in the year 1610. Since then, progressively more powerful telescopes and space probes have refined our original conception of this disc. Saturn's disc is actually many thin rings, mostly made of particles of ice abd rock. The largest rings, A and B, are separated by the Cassini dividion. The fainter C and D rings are inside the B, and F ring lies beyond the A. The gaps are created by the paths of Saturn's moons: the /cassini division by Mimas, the smaller Encke gap by pan. The gaps on either side of the F ring are made by Prometheus on the inside and Pandora on the outside.