![]() The researchers suggested that their findings could help understand more broadly how particles are energized and also give them a clearer picture of how events on the sun affect space near Earth as well as the technological infrastructure we have there, such as satellites.įor Schroeder, there is another much simpler benefit from this kind of research. Such a study would have been impossible in space given that researchers cannot predict when aurora will occur and wouldn’t be able to account for other factors in the cosmos, they said. The researchers used what’s known as the Large Plasma Device at the Basic Plasma Science Facility at the University of California, Los Angeles to re-create the interaction between Alfvén waves and electrons. “Nobody had actually ever measured this before between electrons and Alfvén waves,” Schroeder told NPR. While scientists had assumed for decades that Alfvén waves were responsible for speeding up the electrons, this laboratory experiment has produced the only definitive proof. (Austin Montelius/College of Liberal Arts and Sciences, University of Iowa) What the experiment showed An illustration shows how electrons “surf” on passing Alfvén waves, which launch electrons at high speeds into Earth’s atmosphere where they create the aurora. The excited electrons eventually calm down and release light, which is what we see as the aurora. When the electrons reach Earth’s thin upper atmosphere, they collide with nitrogen and oxygen molecules, sending them into an excited state. If they were moving with the right speed relative to the wave, they would get picked up and accelerated.” ![]() “In order to surf, you need to paddle up to the right speed for an ocean wave to pick you up and accelerate you, and we found that electrons were surfing. “Think about surfing,” said Jim Schroeder, an assistant physics professor at Wheaton College and the article’s lead author. Sometimes electrons hitch a ride on these superfast Alfvén waves, reaching speeds as high as 45 million miles per hour as they hurtle downward. On the same space highway are electrons also traveling toward Earth but not as fast as the Alfvén waves. As those waves get closer to Earth, they move even faster thanks to the planet’s magnetic pull. ![]() In some cases, the sun’s disturbances are so strong that they yank on the Earth’s magnetic field like a rubber band, pulling it away from our planet.īut, like a taut rubber band when it’s released, the magnetic field snaps back, and the force of that recoil creates powerful ripples known as Alfvén waves about 80,000 miles from the ground. The sun is volatile, and violent events there such as geomagnetic storms can echo out into the universe. “But no one had ever come up with a definitive demonstration that the Alfvén waves actually accelerate these electrons under the appropriate conditions that you have in space above the aurora.” How the aurora form “It was sort of theorized that that’s where the energy exchange is occurring,” said Gregory Howes, associate professor of physics and astronomy at the University of Iowa. ![]() That creates cosmic undulations known as Alfvén waves that launch electrons at high speeds into Earth’s atmosphere where they create the aurora. Physicists have long speculated about what gives rise to this very specific light phenomenon that occurs in the Earth’s polar regions.Īn article published in the journal Nature Communications this week suggests that the natural light show starts when disturbances on the sun pull on Earth’s magnetic field. Not even knowing for sure what causes them. Nothing can ruin our joy in the aurora borealis, or northern lights, those ribbons of blue, green and violet light that cascade from the sky. ![]() (Jonathan Nackstrand/AFP via Getty Images) Northern lights (aurora borealis) illuminate the sky over Reinfjorden in Reine, on Lofoten Islands, Arctic Circle, on September 8, 2017. ![]()
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