LAUSR

Juno observed the low-altitude polar region during perijove 1 on 27 August 2016 for the first time. Auroral intensity and false-color maps from the UVS instrument show extensive diffuse aurora observed equatorward of the main auroral oval. Juno passed over the diffuse auroral region near the System III longitude of 120°–150° (90°–120°) in the northern (southern) hemisphere. In the region where these diffuse auroral emissions were observed, the JEDI and JADE instruments measured nearly full loss cone distributions for the downward-going electrons over energies of 0.1–700 keV, but very few upward-going electrons. The false-color maps from UVS indicate more energetic electron precipitation at lower latitudes than less energetic electron precipitation, consistent with observations of precipitating electrons measured by JEDI and JADE. The comparison between particle and aurora measurements provide first direct evidence that these precipitating energetic electrons are mainly responsible for the diffuse auroral emissions at Jupiter.