Images: NASA uncovers secret of the Northern Lights

NASA's fleet of five THEMIS (Time History of Events and Macroscale Interactions during Substorms) satellites have discovered what turns on the Northern Lights. Researchers say "an explosion of magnetic energy a third of the way to the moon powers substorms, sudden brightenings, and rapid movements of the aurora borealis" or Northern Lights.

The key to the auroras is magnetic reconnection, which NASA describes as "stressed magnetic field lines that suddenly snap to a new shape, like a rubber band that's been stretched too far," causing a burst of light and movement near the northern and southern poles. "We discovered what makes the Northern Lights dance," said UCLA's Vassilis Angelopoulos, who is the principal investigator for the THEMIS mission.