What causes the shimmering, ethereal Northern Lights to suddenly brighten and dance in a spectacular burst of colorful light and rapid movement?

For 30 years, there have been two competing theories to explain the onset of these substorms

One theory is that the trigger happens relatively close to Earth, about one-sixth of the distance to the moon.

A second theory says the trigger is farther out, about one-third of the distance to the moon, and involves a different process: When two magnetic field lines come close together due to the storage of energy from the sun, a critical limit is reached and the magnetic field lines reconnect

"Our data show clearly and for the first time that magnetic reconnection is the trigger,"

"Reconnection results in a slingshot acceleration of waves and plasma along magnetic field lines, lighting up the aurora underneath even before the near-Earth space has had a chance to respond.