Aurora Event Trigger Found

Kapow! When Earth's magnetic field snaps and reconnects, the resulting energy pulse (yellow streaks), called a substorm, triggers auroras (inset) a few minutes later.

Credit: NASA/GODDARD (Walt Feirner)


Skywatcher Mark Urwiller caught this stunning view of the aurora borealis, also known as the northern lights, from his vantage point five miles outside Kearney, Nebraska. Urwiller photographed the light show the evening of May 14, 2005.

"We discovered what sparks the magnificent light show of the aurora," said THEMIS principal investigator Vassilis Angelopoulos, a space scientist at the University of California, Los Angeles.

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

We need to understand this environment and eventually be able to predict when these large energy releases will happen so astronauts can go inside their spacecraft and we can turn off critical systems on satellites so they will not be damaged ... This has been exceedingly difficult in the past, because previous missions, which measured the plasma at one location, were unable to determine the origin of the large space storms. To resolve this question properly requires correlations and signal-timing at multiple locations. This is precisely what was missing until now.

The research is detailed in the July 24 online edition of the journal Science.

A flotilla of NASA probes has solved the 30-year mystery behind the most colorful aurora displays on Earth and the explosive magnetic "substorms" that spawn them. It's been a long journey to pinpoint the trigger event for auroras, but it has at last been discovered.

This research should go a long way to providing more accurate space weather predictions. More here.