Source of magnetic substorms within magnetosphere
Sequence of images showing Jupiter's magnetosphere (frame 1) and Earth's magnetosphere (frame 2). Dr. Elena Kronberg and colleagues have studied periodic magnetic substorms at Jupiter and found them to be connected to the constant release of matter by the Jovian satellite Io (frame 3).
Comparing their findings with Cluster observations of magnetic substorms at Earth leads them to conclude that certain periodic substorms at Earth can also be driven from within Earth's magnetosphere, rather than externally by solar activity. For Earth the cause could be mass-loading from the plasmasphere.