Magnetic fields are windows into planetary interiors. Saturn’s  magnetic field continues to offer surprises since the first in-situ measurements  made during the Pioneer 11 Saturn flyby. The Cassini mission entered the Grand  Finale phase in April 2017, during which time the spacecraft dived through the  gap between Saturn’s atmosphere and the inner edge of the D-ring 22 times before  descending into the deep atmosphere of Saturn on Sep. 15th 2017. The  unprecedented proximity to Saturn (reaching ~ 2550 +/- 1290 km above the cloud  deck) and the highly inclined nature of the Grand Finale orbits provided an  ideal opportunity to decode Saturn’s internal magnetic field and the  electromagnetic environment between Saturn and its rings.  

Here we will report new features of Saturn’s magnetic field  revealed by measurements from the Cassini Grand Finale phase. We will show a  newly discovered low-latitude inter-hemispherical field-aligned current (FAC)  system, the directly determined northward offset of Saturn’s magnetic equator  and its “longitudinal” variations, small-scale yet highly consistent magnetic  structures along the latitudinal direction. Observational constraints on the  time variation of Saturn’s internal magnetic field will also be presented. We  will discuss how these latest measurements provide a new perspective on  answering some key questions concerning Saturn’s interior: level of differential  rotation, the existence and extent of stable stratification, and the size and  nature of the central core. Implications on the properties of “ring ionosphere”  will be discussed as well.