Planetary magnetospheres provide natural laboratories for the study of space plasmas, and Jupiter’s magnetosphere in particular acts as a bridge between those phenomena we can study in detail at Earth, and those beyond the solar system that we can only glimpse through telescopes. Jupiter’s auroras have been studied for many years with increasing sensitivity and resolution, but the James Webb Space Telescope offers a revolutionary perspective of these spectacular emissions. We present Webb observations of Jupiter’s infrared auroral H3+ emission, exhibiting variability on timescales down to seconds. Together with simultaneous Hubble Space Telescope ultraviolet observations, these results imply an auroral H3+ lifetime of 150s, and that H3+ cannot efficiently radiate heat deposited by bursty auroral pre- cipitation.However,H3+ radiation is particularly efficient in a dusk active region, which has no significant ultraviolet counterpart. The cause of such emission is unclear. We also present observations of rapid eastward-travelling auroral pulses in the dawn side auroral region and pulsations that propagate rapidly along the Io footprint tail. Together, these observations open a diagnostic window for the jovian magnetosphere and ionosphere. We also preview a new Jovian hybrid Monte-Carlo auroral ionosphere code and some results arising therefrom; e.g. dependence of Pedersen conductance and UV intensities on field-aligned current using realistic precipitating electron energy spectra.
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