It took 25,000 supercomputer processors and 11 days to calculate the motions of 180 billion simulated electromagnetic particles in space. But the effort may have yielded at least a partial resolution to a longstanding mystery: What makes the aurora borealis leap and glow?
A group of scientists at the Massachusetts Institute of Technology (MIT) employed the Kraken, a 112,000-processor supercomputer—one of the world’s largest such machines—to calculate the potential origin of the supercharged electrons that stream in along Earth’s magnetic lines to the poles, causing the phenomenon that we know as the northern and southern lights. Kraken is housed at the National Institute for Computational Science at Oak Ridge National Laboratory in Tennessee.
Routinely, the solar wind blows toward the earth, elongating its magnetic field the way one stretches a rubber band and creating a configuration known as the magnetotail, which streams off the earth away from the sun. (Picture Mother Earth’s hair blowing straight back in a stiff breeze.)
The normally parallel magnetic field lines are pushed farther and farther back until the tail tapers and they reconnect. This reconnection makes the lines snap, catapulting supercharged electrons toward Earth. Those electrons smash into molecules in the upper atmosphere and are guided by the planet’s magnetic lines toward the poles, where they erupt in light.
Physicists have always wondered where in space these electrons got their charge. One candidate is somewhere inside the magnetotail, but scientists traditionally believed that it did not contain any regions large enough to produce the necessary volume of charged electrons, according to Space.com.
The computer simulation, however, showed that the region where these particles are energized is 1,000 times larger than previously thought—ample for producing the charge necessary to spark the aurora borealis, the MIT study found.
Jan Egedal, an associate professor of physics at MIT and a researcher at the Plasma Science and Fusion Center, worked with MIT graduate student Ari Le and William Daughton of the Los Alamos National Laboratory (LANL), to solve what MIT News calls a “space conundrum.” Their results were published in the February 26 issue of the journal Nature Physics.
Researchers still don’t know whether these particles directly cause the aurora borealis, Egedal told Indian Country Today Media Network. But their origin is now known, or at least strongly suspected.
“We just had to run the simulations with the right parameters, and had to have a big enough computer to do it,” Egedal said. “We don’t really know yet if there’s a direct conversion into the aurora borealis or if there’s an intermediate process.”
Taking it a step further, solar flares like the one that ignited the aurora borealis in January erupt in a similar configuration—stretched bands of magnetism that snap and release huge amounts of energy—and could conceivably be calculated by increasing the computation parameters a hundredfold, Egedal said.
In this first video Egedal himself explains the phenomenon, with graphics.
Too much information? The bottom video lets you simply enjoy the view: the aurora borealis over Turtle Island, a.k.a. the U.S. and Canada, as seen from the International Space Station at the end of January 2012.