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.
- I wondered why the baseball was getting bigger. Then it hit me.
- Police were called to a day care where a three-yearold was resisting a rest.
- Did you hear about the guy whose whole left side was cut off? He’s all right now.
- The roundest knight at King Arthur’s round table was Sir Cumference.
- The butcher backed up into the meat grinder and got a little behind in his work. To write with a broken pencil is pointless.
- When fish are in schools they sometimes take debate.
- The short fortune teller who escaped from prison was a small medium at large.
- A thief who stole a calendar got twelve months.
- A thief fell and broke his leg in wet cement. He became a hardened criminal.
- Thieves who steal corn from a garden could be charged with stalking.
- We’ll never run out of math teachers because they always multiply.
- When the smog lifts in Los Angeles, U.C.L.A .
- The math professor went crazy with the blackboard. He did a number on it.
- The professor discovered that her theory of earthquakes was on shaky ground.
- The dead batteries were given out free of charge.
- If you take a laptop computer for a run you could jog your memory.
- A dentist and a manicurist fought tooth and nail.
- A bicycle can’t stand alone; it is two tired.
- A will is a dead giveaway.
- Time flies like an arrow; fruit flies like a banana.
- A backward poet writes inverse.
- A chicken crossing the road: poultry in motion.
- If you don’t pay your exorcist you can get repossessed.
- With her marriage she got a new name and a dress.
- Show me a piano falling down a mine shaft and I’ll show you A-flat miner.
- When a clock is hungry it goes back four seconds.
- The guy who fell onto an upholstery machine was fully recovered.
- A grenade fell onto a kitchen floor in France, resulted in Linoleum Blownapart.
- You are stuck with your debt if you can’t budge it.
- Local Area Network in Australia: The LAN down under.
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- A boiled egg is hard to beat.
- He had a photographic memory which was never developed.
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- He broke into song because he couldn’t find the key.
- A calendar’s days are numbered.
- Those who get too big for their britches will be exposed in the end.
- When you’ve seen one shopping center you’ve seen a mall.
- If you jump off a Paris bridge, you are in Seine.
- When she saw her first strands of gray hair, she thought she’d dye.
- Bakers trade bread recipes on a knead to know basis.
- Santa’s helpers are subordinate clauses.
- Acupuncture: a jab well done.