Looking through the oval window

Space weather is controlled by the dynamic coupling between the solar wind and the magnetosphere, mediated by magnetic reconnection. Data from NASA's IMAGE spacecraft show changes in the auroral oval that reveal more about substorms, a key manifestation of the reconnection process. In particular, substorm magnitude is determined by the amount of magnetic flux previously stored in the magnetosphere, which may in turn be controlled by the strength of the ring current. This suggests that internal feedback processes modulate the magnetosphere's response to extreme solar wind conditions.