The breathtaking rings of Saturn dominate the image below. But you might notice something else. See the small dots of light in the bottom right and top left? Those are two of Saturn’s smaller moons.
They don’t spew water into space like Enceladus or have a dense atmosphere like Titan, but that doesn’t mean they don’t have their own uniqueness.
Pan (seen in the bottom right) is the innermost of Saturn’s known moons. With a mean radius of just 8.8 miles, the tiny moon helps keep the Encke Gap (the opening in Saturn’s A ring) clear. While keeping the 200-mile gap clear, Pan kicks up ‘waves’ in the ring material around it.
Particles making up the rings move at different speeds. The edge closest to Saturn moves faster than Pan. The edge further away moves slower. Because of this, particles on each side receive a gravitational ‘kick’ as they move past Pan. This kick leads to the particles bunching up and creating waves. Here’s another recent image showing these waves forming.
Pan resembles a walnut as it cruises between Saturn’s rings.
Atlas (seen in the top left) orbits slower than Pan, but does the same job. It helps keep the gaps between the rings clear. It’s this clean up that is also believed to give the pair their shape.
As the two clear the gaps between the rings, particles gather near their equators giving them their bulges.
Waves caused by Saturn’s moons
The best visual example is from Saturn’s small moon Daphnis. In 2009, Cassini captured a stunning image showing the structure of these waves. Not the vertical shadows to the left of the moon.
Scientists measured the shadows and believe the vertical structures range from one-third to one mile high.
Image credits: NASA/Cassini