Prometheus’ effect on Saturn’s ropy F ring is evident in this photo from Cassini, taken March 7, 2009. As the irregularly-shaped shepherd moon approaches the ring material in its looping orbit around Saturn, it draws material from the ring in towards itself, warping and stretching the ring particles into waving streamers that eventually settle and snap back into place. It’s a very visual demonstration of gravity at work.
At its widest, Prometheus is about 92 miles across.
Stars are in the background, with one visible through the rings at center bottom.
Raw image credit: NASA/JPL/Space Science Institute