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Physicists explain the new aurora


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For millennia, humans in high latitudes have been fascinated by the aurora, the northern lights and the southern lights. Even after all this time it seemed that the ribbons of light dancing over the world remained a secret.

In a new study, a physicist led by the University of Iowa reported a new feature of the Earth̵

7;s atmospheric light show. By examining videos taken nearly two decades ago, the researchers described cases where part of diffused aurora – a faint, background-like glow with a more vibrant glow that is often associated And Aurora will darken as if being scrubbed with a giant blotting paper. After a while, the blackout reappeared again.

The researchers say the behavior they call “diffuse auroral erasers” was never mentioned in the scientific literature. The research results appear in the file. Journal of Space Physics, Geophysics Research.

Aurora is formed when electrically charged particles flow from the sun, called the solar wind, interacting with the Earth’s protective magnetic bubble. Some of these particles escape and fall into our planet, and the energy released during the collision with the Earth’s atmospheric gases produces aurora-related light.

“The biggest thing about these erasers that we never knew existed. But I knew it was there, ”said Allison Jaynes, an assistant professor in the department of physics and astronomy at Iowa and co-author of the study. “It begs the question: is this a common phenomenon that is overlooked or a rare one.

“Knowing that they exist means there is a process that is building them,” Jaynes continues, “and it may be a process that we haven’t started watching because we didn’t even know it was happening until now.”

The famous northern lights and southern lights have been studied for thousands of years. But they are still a secret. In a new study, physicists led by the University of Iowa describe a new phenomenon they call the “Diffuse Aurora Eraser” where patchy background glow is removed, then intensified and reappears. Credit: Riley Troyer, University of Iowa.

On March 15, 2002, physicist David Knudsen at the University of Calgary set up a video camera in Churchill, the town of Hudson Bay, in Canada, to film Aurora. Knudsen’s group was frustrated. little The forecast calls for clear, dark skies that are usually the perfect conditions for viewing Aurora. But there was no dazzling light. Still, the team used specially designed cameras to capture low-level light, just like night vision goggles.

Scientists see mostly the darkness as they look upward with their own eyes. Instead, the cameras store all sorts of neurological activity, including the anomalous sequence in which areas of the diffused aurora disappear and then return.

Knudsen watched the video while recording was written in his notebook. A sparkling “black-out” glow that fills in seconds. “

“What surprised me and what made me write it in the notebook was that when the patch lit up and turned off the diffused aurora, the background was wiped off,” said Fort Dodge native Knudsen. Iowa said, a native who has studied the aurora for more than 35 years and was a co-author on the study. “There’s a hole in the diffused aurora, then it will come back in half a minute or so. I’ve never seen anything like that before.”

The note was put aside, and the video was not studied until Jaynes, of Iowa, sent it to graduate student Riley Troyer to review.Jaynes learned of Knudsen’s recordings at a 2010 scientific conference and cited the notes. Of the eraser in her doctoral dissertation on the aurora scattering a few years later. Now on a faculty in Iowa, she wants to learn more about the phenomenon.

“I knew something was there, I knew it was different and unique,” said Jaynes, assistant professor in the Department of Physics and Astronomy. “I have some ideas how to analyze this. But I haven’t done that yet, I sent it to Riley, and he went further, figuring out how to analyze his own data and draw some important conclusions. ”

Troyer from Fairbanks, Alaska, was delectable.

“I’ve seen hundreds of Aurora grow,” said Troyer, who is currently studying a third-year PhD in Iowa. “They are part of my legacy which is something I can study while maintaining a relationship with where I came from.”

Troyers have created a software program to input frames in the video when a faded eraser is visible. In total, he listed 22 eraser incidents in a two-hour recording.

“The most valuable thing we have found is the display of the time the aurora will go from the eraser event. (When the diffused aurora is removed) to fill or refill the color, “said Troyer, the author of the document. “And how long does it take to go from that deleted state to a diffused aurora? Such a value will help in the modeling of the future magnetic fields.”

Jaynes said that learning about diffuse auroral erasers is similar to studying DNA to understand the entire human body.

“Particles falling into the atmosphere from space can affect our atmosphere and our climate,” Jaynes said, “although diffused aurora particles may not be the main cause. Rather, it is a collection of small buildings that help us understand the aurora system as a whole and potentially expand our understanding of how the aurora formed on other planets in our solar system. ”

Image: Aurora and sunrise

More information:
RN Troyer et al, The Diffuse Auroral Eraser, Journal of Geophysical Research: Space Physics (2021). DOI: 10.1029 / 2020JA028805

Provided by the University of Iowa

Reference: Physicists explain the new aurora (2021, May 6) .Retrieved on May 6, 2021 from https://phys.org/news/2021-05-physicists-aurora.html

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