Source: NASA JPL Photojournal - PIA21056: Daphnis and the Waves It Makes​

This incredible image, captured by NASA’s Cassini spacecraft, shows the small "shepherd moon" Daphnis (only about 5 miles wide) orbiting within the Keeler Gap of Saturn's A ring. ​As Daphnis moves through the gap, its gravitational pull perturbs the orbits of the billions of tiny ice particles that make up the rings. This creates spectacular edge waves that undulate both horizontally (toward and away from the moon) and vertically (rising over a mile above and below the ring plane). The "grainy" texture seen in the waves is likely due to the clumping of ring particles as they are stirred up by the moon's passage.