Tracking plasma rotation speeds in Saturn's magnetosphere

Abstract

Researchers are learning more about the dynamics of Saturn's magnetosphere by applying a technique that is commonly used to study Earth's aurora. Using data from the magnetospheric imaging instrument on the Cassini spacecraft, Carbary and Mitchell tracked blobs of energetic neutral hydrogen atoms within Saturn's magnetosphere by creating keograms—time versus latitude plots assembled from multiple images, providing an instantaneous global view of azimuthal speeds of the blobs. The energetic neutral atoms serve as “imagers” of the ion population of a magnetosphere because they originate from charge exchange between neutral atoms and energetic ions.