Swirls in Saturn's cloud-tops. Courtesy NASA/JPL-Caltech

The surface of Saturn's moon Dione, up close. Courtesy NASA/JPL-Caltech

Tiny moon Janus, seen before Saturn's rings, with massive moon Titan beyond. Courtesy NASA/JPL-Caltech

Saturn's moon Rhea, with Izanagi Crater at center. Courtesy NASA/JPL-Caltech

Saturn's horizon seen through its thin rings. Courtesy NASA/JPL-Caltech

Small moon Mimas, seen against Saturn's horizon. Courtesy NASA/JPL-Caltech

A "knot", or small disturbance in one of Saturn's outer rings. Courtesy NASA/JPL-Caltech

Closeup of small, cratered moon Hyperion. Courtesy NASA/JPL-Caltech

Saturn's moon Enceladus, seen just in front of Saturn. Courtesy NASA/JPL-Caltech

Saturn's polar region. Courtesy NASA/JPL-Caltech