HST observations of planetary aurorae, a unique tool to study giant magnetospheres

Ultraviolet (UV) planetary astronomy is a unique tool to probe planetary environments of the solar system and beyond. But despite a rising interest for new generation giant UV telescopes regularly proposed to international agencies, none has been selected yet, leaving the Hubble Space Telescope (HST) as the most powerful UV observatory in activity. HST regularly observed the auroral emissions of the Jupiter, Saturn and Uranus systems, leading to significant discoveries and achievements. This rich legacy remains of high interest for further statistical and long-term studies, but new observations are necessary to comparatively tackle pending questions, under varying solar or seasonal cycles.