An eye on the auroras: coordinated observations of Jupiter from Hubble and Juno

One could think that with a spacecraft orbiting a planet, there would be no further need for Earth-based observations. One could not be more wrong. In this presentation, we will report on recent results of coordinated observations of the UV auroras from Hubble’s STIS instrument and measurements from the Juno spacecraft currently orbiting Jupiter. It began during the approach phase, when Juno was still cruising in the interplanetary medium, serving as a solar wind monitor as STIS scrutinize the auroral response to solar wind shocks. Other studies made use of the field and particle measurements on board Juno to characterize the size of the magnetosphere, the presence of magnetic reconnection or the stretching of the magnetic field lines combined with HST observations of the auroras in order to connect local and global scales. Others made use of HST observations to continue the observations of the auroras after Juno flew too far away from Jupiter to obtain resolved images, effectively extending the time interval of continuous observations and giving access to long-timescale phenomena, such as the complete unfolding of dawn storms. Finally, we will briefly discuss previously impossible simultaneous observations of both poles. In conclusion, Earth-based observations of the UV auroras are a crucial tool to maximize the outcome of spacecraft mission, offering context, continuity and complementary views of the complex phenomena taking place in planetary magnetospheres.