When a snowball becomes a moon: When enough stuff accretes onto a body within Saturn's rings, they can become a Shepherd Moon. These moons rule over their own ring gaps. They also shepherd the rings, keeping them in order. If they have enough gravity, they can create disturbances in the edges of their gaps. Daphnis orbits within the Keeler Gap and as the material passes it the moon gives it little tugs creating rhythmic waves.
NASA/JPL-Caltech/SSI/CICLOPS/Kevin M. Gill
@kevinmgill I'm guessing the moon isn't geosynchronous because ripples from an oblong shaped moon suggest rotation, or possibly the density of the ring isn't constant and the gravity differences of the ring tug on pull on the nearer sides of the moon. If the moon isn't currently spinning. I bet you could use the ripples to determine when it was spinning and for how long. Does this make any sense?
