At the heart of Jupiter’s aurora; at the crossroads of Astrophysics Geophysics and Plasma Physics

Auroral physics is at the intersection of more general fields of physics such as Astrophysics, Geophysics and Plasma Physics. In particular, the giant planets Jupiter and Saturn may be seen as slow rotating pulsars. For these two planets, there is a direct link between this pulsar-like behaviour and the auroral processes that are taking place in their atmosphere. We will take the example of Jupiter to illustrate haw the aurora is generated in the magnetosphere as a result of the volcanic activity of the moon Io. The ultraviolet aurora of Jupiter is conveniently described in terms of components located inside (poleward of) or outside (equatorward of) the main oval emission. However, these components may also be discriminated by their temporal behaviour, where the narrowest parts of the main “oval” remain relatively stable over time periods of several hours, and the satellite footprints show large variability with timescales of minutes. Inside the main emission, at the heart of the aurora, the so-called polar aurora, presumably corresponding to the polar cap mixing open and closed magnetic field lines, is characterized by rapid motions taking the form of swirls, giving rise to the “swirl region” and by beatings in the “active region”. This delicate auroral region is difficult to apprehend because of its ever-changing shape and because of the lack of appropriate tools to study it.