THEMIS probes view auroral substorms, bowshock explosions

The hear of the sun's atmosphere propels charged particles and strong magnetic fields outward as a solar wind. The Earth's magnetic field (blue) is distorted by the fierce wind as the solar energy seeks a way in. The five THEMIS probes, strung out like pearls on a string in their orbit around Earth, hope to discover how and where the solar energy leaks through the magnetosphere and generates the Northern and Southern Lights. (Note that the figure is not to scale.). (NASA image)