 Source: Discovery
Dec. 12, 2007 -- Scientists think they have
discovered the energy source of auroras borealis, the spectacular color
displays seen in the upper latitudes of the Northern Hemisphere.
New data from NASA's Themis mission,
a quintet of satellites launched this winter, found the energy comes
from a stream of charged particles from the sun flowing like a current
through twisted bundles of magnetic fields connecting Earth's upper
atmosphere to the sun.
The energy is then abruptly released in the form of a shimmering
display of lights, said principal investigator Vassilis Angelopoulos of
the University of California at Los Angeles.
Results were presented Tuesday at the American Geophysical Union meeting.
In March, the satellites detected a burst of Northern Lights over
Alaska and Canada. During the two-hour light show, the satellites
measured particle flow and magnetic fields from space.
To scientists' surprise, the geomagnetic storm powering the auroras
raced 400 miles in a minute across the sky. Angelopoulos estimated the
storm's power was equal to the energy released by a magnitude 5.5
earthquake.
"Nature was very kind to us," Angelopoulos said.
Although researchers have suspected the existence of wound-up
bundles of magnetic fields that provide energy for the auroras, the
phenomenon was not confirmed until May, when the satellites became the
first to map their structure some 40,000 miles above the Earth's
surface.
Scientists hope the satellites will record a geomagnetic storm next year and end the debate about when the storms are triggered.
Related Links:
Irene Klotz's blog: Space Diary
NASA's Themis mission
How Stuff Works: How does the aurora borealis (the Northern Lights) work?
See also:
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