Stories tagged northern lights
Aurora mystery comes to light
in Earth and Space Science, Physical Science, Energy Transformations, and Forces of Nature
Northern Lights over Minneapolis: Aurora borealis dance over Lake Harriet, November 6, 2004
Courtesy Mark RyanMany years ago, three friends and I were heading home from a road trip to western Canada. It was about 2:30 in the morning, and I was driving while everyone else was sleeping. I was probably half-asleep myself. But as we chugged along Highway 2 near the outskirts of Bemidji, Minnesota, something in the upper corner of the windshield caught my eye. When I looked up, the sight was so spectacular I immediately pulled over and woke everyone up to see it. My friends were none too happy as I coaxed them out of the van into the cold northern Minnesota night.
Above us, the night sky was alive with the most incredible display of the Northern Lights I have ever witnessed. Bright, vibrant fingers of yellow, blue, red, and green light spread out from a point overhead, like a brilliant hand reaching down from the black sky. I’ve never seen colors like that since. The display was something I’ll never forget and it’s hard to convey how beautiful it actually was, but let me just say my friends soon discarded any thoughts of pummeling me with their fists.
Now, scientists have figured out the mystery behind the phenomenon. According to a new study published in the journal Science, the catalyst of the aurora borealis (and their southern counterpart aurora australis) takes place way out in space about 80,000 miles from Earth during an event called magnetic reconnection.
"Our data show clearly and for the first time that magnetic reconnection is the trigger," said Vassilis Angelopoulos, the project’s principal investigator. "Reconnection results in a slingshot acceleration of waves and plasma along magnetic field lines, lighting up the aurora underneath even before the near-Earth space has had a chance to respond."
The data was gathered by five strategically positioned satellites (a NASA mission known as THEMIS) and compared with that from ground-based detectors.
The process actually begins on the Sun. Turbulent activity on its surface sends out massive energy bursts via the solar wind that interact with the Earth’s magnetic fields and cause all sorts of havoc with our power grids and communication networks. They also create wonderful auroras. But these massive solar outbursts are only occasional, occurring maybe 10 times a year. More frequently – about every three or four hours - the geomagnetic fields are bombarded by substorms; smaller energy bursts that also create auroras. But don’t let the diminutive name deceive you. The energy generated by each substorm is huge, anywhere between one million to two million amps over one or two hours. The THEMIS project determined that, during substorms, the Earth’s magnetic field lines are stretched out like rubber bands building up tremendous amounts of energy before suddenly snapping and flinging charged particles back toward the Earth’s poles. The results are the dancing auroras seen in the northern and southern regions.
Magnetic reconnection is common throughout the known Universe and has been suspected by many as the trigger of auroras. For three decades, though, a competing theory argued the auroras were triggered much closer to Earth, by the disruption (or short-circuit) of charged ions interacting with the magnetic field.
But the new data seems to show otherwise. During a substorm studied in February, the satellites’ data showed the magnetic reconnection occurred first, followed soon after by an aurora display. Only after the display was the short-circuit observed.
Looks like the 30-year debate may be over.
LINKS
Tags : 
Good lookin', bad soundin': Radiowaves that get caught up in the Northern Lights are creating some annoying noises that zap out into space.
Courtesy NASANo wonder aliens want to attack the Earth with such regularity in the movies. From out in space, we sound pretty annoying, like that renter in the apartment above you who insists on playing Yoko Ono records at 2:30 in the morning.
You laugh, but new recordings from space show that Earth, our home, makes an array of nasty sounds that ring out across the universe.
Scientists have actually known about this phenomenon since the 1970s. But today we have some audio evidence of this annoying noise. So what’s happening?
There’s a bunch of radiation created high above our planet. Solar winds blow it into Earth’s magnetic field and then things start to get loud. Basically, this radiation gets sucked into the same conditions that cause the Northern Lights. While they look great, they sound horrible – sorta like Brittney Spears.
Earth’s ionosphere keeps the radio waves created in this action from coming down toward us, which is a good thing. That’s because they’re about 10,000 times stronger than any radio signals we have on our planet.
Satellites from the European Space Agency's Cluster mission, however, have now detected strong beams of these annoying radio waves out in space.
Click here to hear a sample of what this space noise sounds like. Personally, I think I’ve experienced this sound, much quieter, after eating a bad burrito.
Streaming space light: Satellites on NASA's Themis mission have discovered what may be some of the mysteries behind the northern lights. Charged particles from the sun are blasting through magnetic fields stretching out from Earth's upper atmosphere, bursting with the energy of a medium earthquake.
Courtesy NASAI know the source of the energy that powers the Christmas lights in my home’s windows: the outlet on my wall. No surprises there.
But today scientists announced that they have found what they believe is the energy source behind the spectacular views that make up the northern lights. NASA’s Themis mission has used five satellites to track down this magical, astronomical phenomenon.
What’s been discovered is that charged particles from the sun are flowing through space and are twisted through magnetic fields that link Earth’s upper atmosphere to the sun.
The satellites were launched last winter and on one two-hour span of time, measured the particle flows while northern lights were shimmering over Alaska and Canada in March.
If you’ve ever seen the northern lights, you know how cool and magical they can look. But you really wouldn’t want to get too close.
The same satellites measured the forces flowing through the March light show and found that the charged particles were moving around 400 miles per hour. The movement and energy release of their passing through the magnetic field was about the same as a 5.5 magnitude earthquake.
The northern lights, or aurora borealis, are caused when particles streaming from the Sun strike the Earth's atmosphere. Solar activity is very difficult to predict -- you often get only one or two day's notice between the eruption of a solar storm and the aurora.
But Charles Deehr, Professor of Physics at the University of Alaska Fairbanks, has noticed a couple of recent "coronal holes" on the Sun that have been more stable than usual. Assuming these stay active, they could lead to aurora activity on the following dates:
Jan 15-22
Jan 29-Feb 6
Feb 12-19
Feb 25-Mar 2
Mar 11-18
Mar 24-30.
Deehr categorizes these events as "moderately active," meaning they may not be visible from the United States (or only the very northernmost part, above the 45th parallel). But if you're planning a trip to Canada or Alska during these times, look to the sky around midnight and tell us what you see.
Aurora, 12/14/06: Photo by Eugene Dillenburg.
Did anybody see the northern lights this week? I went out Thursday night, and it was awesome!
I headed out about 11:00 pm EST. Temps in the mid-40s -- not bad for mid-Michigan in mid-December! I walked a couple of blocks to a park near my apartment which I knew had a big field surrounded by trees, and no lights. On my way, I could see the sky glowing a pale green, as if the lights of the city were reflecting off a low cloud. Only, there were no clouds last night, and there's nothing but farmland north of Lansing.
Please contact us if you have questions about the rights on this image.
Aurora borealis: (Photo courtesy Sami Koykka)
A friend passed along an E-mail from Parke W. Kunkle, President of the Minnesota Planetarium Society:
"Hi, all.
This email contains information about potential aurora for the next few days....There's a big active region now on sun. Watch its progress.
Normally I'd watch it on [the NASA site], but that instrument is down for routine maintenance until Tuesday.
I think there is a good chance for northern lights the next couple of nights. Just go outside and look north.
If you are being a winter weenie and don't want to go out, check the auroral map.To learn about space weather, try the Exploratorium site.
Or see ongoing information."
(Photo courtesy Sami Koykka)
Please contact us if you have questions about the rights on this image.
Science Buzz and all related activities
Add a new comment