Comparing Electron Radiation Belts and New Lessons from Jupiter

We revisit comparisons between the electron radiation belts of all of the strongly magnetized planets of the solar system; specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Many features are worthy of reexamination in the light of new understandings achieved by such recent missions as the Van Allen Probes at Earth and Juno at Jupiter. One example is the unexpectedly intense radiation belts at the otherwise anemic magnetosphere of Uranus. At Jupiter a key mystery is how such robust high energy tails of the distributions are generated throughout the jovian radiation belt regions. One of the unexpected findings of the Juno mission is just how energetic are the auroral acceleration processes. Upward broadband acceleration commonly extends into the multi-MeV energy ranges (figure) and even > 10 MeV. We investigate here the hypothesis that such auroral acceleration plays a critical role in the seeding the generation of Jupiter’s uniquely energetic electron radiation belts. Time permitting, we also address challenges of applying lessons from planetary radiation belts to electron radiation regions outside of our solar system.