Reading Saturn’s Recent History in its Rings

Saturn’s C ring contains multiple spiral density waves that appear to be generated by asymmetries in Saturn’s gravitational field that rotate at roughly the same rate as the planet. Detailed studies of these waves reveal that they have unusual characteristics which suggest that most of these asymmetries have time-variable periods and amplitudes. Furthermore, the observed properties of these waves enable us to map the history of these asymmetries over the past few decades. This analysis reveals that while a few asymmetries in Saturn’s gravitational field have been steadily accelerating, several others appear to be more transient, appearing and disappearing over the course of a few years. These waves therefore provide new insights into the dynamics and recent history of Saturn’s interior.