Fig. 15.

Ring seismology. The vertical dotted lines are the speeds of non-axisymmetric patterns in Saturn’s rings. Only the patterns that match the planet’s rotation are shown. They could be due to floating masses in the interior of Saturn. For comparison, periods of exterior magnetic fields, radio emissions, and clouds in the atmosphere are shown. Other patterns with speeds twice as fast are likely due to normal mode oscillations of the planet (Hedman and Nicholson 2014)