The enigmatic aurora borealis has kept scientists on a constant quest to understand the mysterious forces behind the spectacular dance of lights that brightens the North sky at night. Auroras can be observed near the Earth’s northern (aurora borealis) and southern (aurora australis) magnetic poles, in colorful green, blue or red displays.
The spectacular events have been linked to geomagnetic substorms, which are powered by explosions of magnetic energy one third of the way to the moon. This triggers the magnetic reconnection phenomenon, when magnetic field lines merge into new shapes, causing the sudden brightening and movement of the aurora borealis.
“We discovered what makes the Northern Lights dance,” said Dr. Vassilis Angelopoulos of the University of California, Los Angeles. Scientists have been trying for decades to find out what exactly triggers the burst of energy in Earth’s magnetosphere.
With the help of the NASA THEMIS satellites, short for Time History of Events and Macroscale Interactions during Substorms, researchers identified the magnetic explosions that produce dynamic changes in the auroral displays.
David Sibeck, THEMIS project scientist at NASA’s Goddard Space Flight Center, explained that the magnetic reconnection releases the energy captured and stored by Earth’s magnetic field lines from the solar wind back toward the Earth’s atmosphere, which creates halos of shimmering auroras circling the northern and southern poles.
Prior to the observations from the THEMIS satellites, there have been two theories regarding the substorms. One theory placed substorms closer to Earth, one-sixth of the way to the moon, where large amounts of particles are sent toward our planet from solar wind currents’ disruptions, causing the burst of light.
The second theory, confirmed by this study, places the substorms one third of the distance to the moon, where magnetic lines are stretched so far back that they snap into a new shape, similar to a rubber band when it is stretched too far, in a phenomenon known as magnetic reconnection.
This is from over a month back, but I really wanted to mention it, both here and on the video. I can explain what his happening there a bit better, using the pictures below, but I always find it exciting when we solve another of the great mysteries.
UPDATE: You can see the video version of this post in these videos. This post is covered in the second one.