Saturn's Ring Waves

Daphnis, 8 kilometers(5 miles)across, occupies an inclined orbit within the 42-kilometer (26-mile) wide Keeler Gap in Saturn's outer A ring. Recent analyses by imaging scientists published in the Astronomical Journal illustrate how the moon's gravitational pull perturbs the orbits of the particles forming the gap's edge and sculpts the edge into waves that have both horizontal and vertical components.

--http://saturn.jpl.nasa.gov