APOD: 2010 August 2 - Prometheus Creating Saturn Ring Streamers (original) (raw)

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2010 August 2

Explanation: What's causing those strange dark streaks in the rings of Saturn?Prometheus. Specifically, an orbital dance involvingSaturn's moon Prometheus keeps creating unusual light and dark streamers in theF-Ring of Saturn. Now Prometheus orbits Saturn just inside the thinF-ring, but ventures into its inner edge about every 15 hours. Prometheus' gravity thenpulls the closest ring particles toward the 80-km moon. The result is not only a stream of brightring particles but also adark ribbon where ring particles used to be. Since Prometheusorbits faster than the ring particles, the icy moon pulls out a new streamer every pass. Above, several streamers or kinks are visible at once. The above photograph was taken in June by the robotic Cassini Spacecraft orbitingSaturn. The oblong moon Prometheus is visible on the far left.