Thursday, July 24, 2008

NASA Satellites Discover What Powers Northern Lights

This press release from NASA touches upon a topic of personal interest.

Researchers using a fleet of five NASA satellites have discovered that explosions of magnetic energy a third of the way to the moon power substorms that cause sudden brightenings and rapid movements of the aurora borealis, called the Northern Lights.

The culprit turns out to be magnetic reconnection, a common process that occurs throughout the universe when stressed magnetic field lines suddenly snap to a new shape, like a rubber band that's been stretched too far.

"We discovered what makes the Northern Lights dance," said Dr. Vassilis Angelopoulos of the University of California, Los Angeles. Angelopoulos is the principal investigator for the Time History of Events and Macroscale Interactions during Substorms mission, or THEMIS.

Substorms produce dynamic changes in the auroral displays seen near Earth's northern and southern magnetic poles, causing a burst of light and movement in the Northern and Southern Lights.

One of my two brief stints in research as an undergrad was in the space physics department at the U of MN looking at auroral substorms. This was back in 2000 before the launch of the THEMIS satellites. I was looking for a good conjunction of the FAST and POLAR satellites at the outset of a substorm over the north polar region. I was unsuccessful, but it was interesting looking at lots of substorm images. These storms engulf a ring surrounding the entire polar region. A lot of energy being released and now we know how!

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