The Aurora at Earth and Jupiter: Similarities and Differences

Dr. Yi-Jiun Su
Laboratory for Atmospheric and Space Physics
University of Colorado, Boulder
Thursday, April 7th, 2:30 PM
Magnetic structures observed in our own solar system and in other celestial configurations are remarkably similar. The vastly differing magnetospheric dimensions are produced by differences in the intrinsic strengths of the associated magnetic fields and plasmas. For example, Jupiter's magnetosphere is enormous when compared with the Earth's. However, as our spacecraft emissaries have discovered, each world exhibits distinctive and unique properties. A prime example of this is found in the comparison of magnetospheric plasma sources at Jupiter and Earth. While Io, Jupiter's most active satellite, serves as the main plasma source for Jupiter's magnetosphere, the source of the Earth's magnetospheric plasma is the solar wind and the ionosphere.
    In this seminar, I will present three types of magnetosphere-ionosphere (MI) coupling processes in the Earth's auroral regions, and suggest that all three types seen on the Earth may be active on Jupiter as well. The Io-controlled Jovian aurora shows evidence of Alfvén-dominated aurora in the footprint of Io, while the extended tail emissions in the downstream region (i.e., Io's wake) are due to electron acceleration from parallel electric field in an upward current region. With our simulation effort, we are not only able to reproduce Alfvénic field and particle signatures commonly observed in the dayside auroral region by the Earth's polar orbiting satellite, but also successfully adapt this numerical model to study the propagation of Alfvén waves in Jupiter-Io interaction.

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