Scientists uncover a mystery behind the northern lights
Published Thursday, July 24, 2008
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CAPE CANAVERAL, Fla. — Scientists have exposed some of the mystery behind the northern lights.
On Thursday, NASA released findings that indicate magnetic explosions about one-third of the way to the moon cause the northern lights, or aurora borealis, to burst in spectacular shapes and colors, and dance across the sky.
The findings should help scientists better understand the more powerful but less common geomagnetic storms that can knock out satellites, harm astronauts in orbit and disrupt power and communications on Earth, scientists said.
A fleet of five small satellites, called Themis, observed the beginning of a geomagnetic storm in February, while ground observatories in Canada and Alaska recorded the brightening of the northern lights. The southern lights — aurora australis — also brightened and darted across the sky at the same time.
These auroral flare-ups occur every two or three days, on average.
A team led by University of California, Los Angeles, scientist Vassilis Angelopoulos confirmed that the observed storm about 80,000 miles from Earth was triggered by a phenomenon known as magnetic reconnection. Every so often, the Earth’s magnetic field lines are stretched like rubber bands by solar energy, snap, are thrown back to Earth and reconnect, in effect creating a short circuit.
It’s this stored-up energy that powers the northern and southern lights or, in other words, causes them to dance, according to Angelopoulos.
An opposing theory has these geomagnetic events occurring much closer to Earth, about one-sixth of the way to the moon. More Themis observations are needed to resolve the debate, said David Sibeck, NASA’s project scientist.
“Finally, we have the right instruments in the right place at the right time, and it’s allowed scientists to be able to make the necessary observations to settle this heated debate once and for all,” said Nicola Fox, a Johns Hopkins University scientist who was not involved in the study.
At present, about 20 of these geomagnetic storms are being analyzed. Scientists hope to eventually learn, via this project, more about the bigger solar storms that occur about 10 times a year and can lead to far more expansive and prolonged northern and southern lights.
The five Themis spacecraft — a NASA acronym standing for Time History of Events and Macroscale Interations during Substorms — were launched aboard a single rocket last year.
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On the Net:
NASA: www.nasa.gov/themis
Community Discussion
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Neat...but I like the old saying better: "WHISTLE AND THE NORTHERN LIGHTS WILL GET BRIGHTER!!!" Try it when it gets to -40 F below this winter and see if it don't make you feel better.
I've seen it done Out_in_the_cold! i thought it was a bunch of malarky, but it works. You have to whistle pretty loud too though.. thru the fingers works pretty good. Crazy stuff, amazing thou :)
LOL, since the bottom edge of the aurora is 60 miles away, you'd have to whistle louder than a train; and the sound will take more than 5 min to get there. The aurora is going to move whether you whistle or not.
According to ancient Greek mythology Themis (meaning "law of nature" rather than "human ordinance"), she "of good counsel," was the embodiment of divine order, law and custom. When Themis was disregarded, Nemesis would bring just and wrathful retribution. She advised Zeus.
All I know is that they are the most amazing natural high you can have. I have seen them red, green, white...over Birch Lake...in Fairbanks...from an airplane. I will stop the car and pull over on Goldstream Rd and watch them everytime. For kids out there, the Disney movie, Brother Bear dipicts them in all their cartoon glory and even that show is awesome to watch (it's good entertainment, not always accurate). UAF museum has a great show too...
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