Saturn's Rings + Atlas, Pandora, Prometheus and Janus

Caption NASA originale: "Saturn hosts its own miniature solar system with an entourage of more than 30 moons. This image shows Saturn's "A" and "F" Rings, along with three of the moons that orbit close to them. From innermost to outermost, tiny Atlas (32 Km across) orbits just outside of the bright "A-Ring" and is seen above center in this view. Prometheus (102 Km across) is visible near lower right. Prometheus and its smaller cohort, Pandora, shepherd the thin, knotted F-Ring. Janus (181 Km across) can be seen near lower left. Janus shares its orbit with the moon Epimetheus. Density waves due to Janus cause some of the bright bands seen in the A-Ring in this image. Prometheus and Atlas also produce waves in the rings, but their wave regions are too narrow to be seen here. The planet's shadow stretches all the way across the main rings in this view. The shadow has an oval shape now but over the next few years it will become more rectangular as the planet orbits the Sun and the angle Sunlight-Rings decreases.