A diffuse core in Saturn revealed by ring seismology

The best constraints on the internal structures of giant planets have historically originated from measurements their gravity fields1–3. These data are inherently mostly sensitive to a planet’s outer regions, stymieing efforts measure mass and compactness cores Jupiter2,4,5 Saturn6,7. However, studies Saturn’s rings detected waves driven by pulsation modes within planet8–11, offering independent seismic probes interior12–14. observations reveal gravity-mode pulsations, which indicate that part deep interior is stable against convection13. Here, we compare structural models with Cassini show can only be explained diffuse, stably stratified core–envelope transition region in Saturn extending approximately 60% radius containing 17 Earth masses ice rock. This gradual distribution heavy elements constrains mixing processes at work Saturn, it may reflect primordial structure accretion history. Like seismograph, oscillations coming interior. State-of-the-art modelling shows Cassini’s ring point convectively diffuse core extends for its contains