Have you every wondered what causes the Northern LIghts (also known as aurora borealis) to dance?
Northern Lights Dance
It’s the result of magnetic reconnection, a process that occurs throughout the universe when stressed magnetic-field lines suddenly snap to a new shape, similar to a rubber band that’s stretched too far. This explosion of magnetic energy powers substorms that cause sudden brightness and rapid movements of the aurora borealis.
“We discovered what makes the Northern Lights dance,” said Dr. Vassilis Angelopoulos of the University of California, Los Angeles, who is the principal investigator for the Time History of Events and Macroscale Interactions during Substorms mission, or Themis. Using five identical NASA Themis satellites (launched in February 2007) and a network of 20 ground observatories located throughout Canada and Alaska, scientists observe these storms. The satellites line up once every four days along the equator and take observations synchronized with the ground observatories. Data captured during these alignments lets scientists precisely pinpoint where, when, and how substorms measured on the ground develop in space.
Using a magnetometer and camera pointed upward, each ground station determines where and when an auroral substorm will begin. The auroral light is measured from particles flowing along Earth’s magnetic field and the electrical currents these particles generate.
The 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. These substorms often accompany intense space storms that can disrupt radio communications and global-positioning system signals and cause power outages.
“As they capture and store energy from the solar wind, the Earth’s magnetic field lines stretch far out into space. Magnetic reconnection releases the energy stored within these stretched magnetic field lines, flinging charged particles back toward the Earth’s atmosphere,” said David Sibeck, Themis project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “They create halos of shimmering aurora circling the northern and southern poles.”
These observations confirm for the first time that magnetic reconnection triggers the onset of substorms. Themis is the fifth mediumclass mission under NASA’s Explorer Program.
For you lovers of cryptic words, here’s something we found circulating the Web.
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