The rich dynamics of Saturn’s rings offer a unique opportunity to study the internal structure of the planet. Like the Sun, Saturn continuously pulsates at low amplitudes due to convective motions in its interior. Although these pulsations are too small to be directly detected, their gravitational interaction with particles in the rings creates density waves at Lindblad resonances in the rings, and these waves can be observed by the Cassini satellite. Measurements of the waves in the rings then tell us the amplitudes and frequencies of Saturn’s pulsations, allowing for seismology to be performed on Saturn. The seismic signatures in the rings differ from prior expectations and indicate Saturn’s internal structure is more complex than originally believed. I will show that the observations can be partially explained by the existence of stable stratification in the deep interior of the planet, likely created by composition gradients between the core and envelope. These composition gradients may be a relic of formation, or they may have built up over time due to helium rain and/or core erosion.
By: Jim Fuller, Postdoc, Caltech
Click for a live broadcast