0 Assigned ID: 652 ----- Attempting Submission 1 (Fri Apr 08 18:16:58 GMT 2016) ----- Jupiter's UV auroral emissions are the brightest in the solar system. They include the main auroral emission, which is associated with a system of corotation enforcement currents, and patches of bright emission called the satellite footprints because they occur at the ionospheric end of field lines linked to Jupiter's moons Io, Europa, and Ganymede. Because the footprints' ionospheric positions are linked to a fixed radial distance in the magnetosphere, changes in the satellite footprint locations are likely due to changes in Jupiter's magnetospheric field configuration. Variability in the main emission location is more complicated by comparison because the main emission can be influenced both by the field configuration and by other factors related to the corotation enforcement current system. We propose to analyze HST images of Jupiter's UV aurora to quantify variability in the satellite footprint locations and main emission. Comparing the variability of these two features will establish the cause of shifts observed in Jupiter's main emission and will provide valuable constraints for models of Jovian magnetosphere-ionosphere coupling. This work is timely because it will provide a framework for the upcoming Juno mission, which will study Jupiter's polar regions. Our work builds upon previous studies of auroral variability but will be the first to focus on images from the Galileo era and make direct comparisons to magnetospheric variability observed in situ. This proposal supports the HST UV initiative and the proposed analysis was not included in the original GO proposals. Solar System 0 Regular false true false SUPPORTED