Cassini’s Christmas Gift: a Peek at Prometheus
Captured on Christmas Day, this is a raw image from Cassini showing Saturn’s F ring buckling inwards at two places due to the gravitational tug of its inner shepherd moon, Prometheus, seen at center.
As the irregularly-shaped moon approaches the ring material in its looping orbit around Saturn it draws material from the ring in towards itself, warping and stretching the fine icy ring particles into waving streamers that eventually settle back into place. It’s a very visual demonstration of gravity at work!
At its widest Prometheus is about 92 miles (148 km) across but only 42 miles (68 km) in width. It orbits Saturn once every 14.7 hours.
Raw image: NASA/JPL/Space Science Institute