Aurora borealis, or the northern lights, is one of Earth's greatest light shows, which is exclusive to regions in higher latitudes. For many years, it had scientists in awe and wonder especially on its mysterious origins.
Scientists have held many speculations about the colorful aurora borealis but these have never been proven not until recently. A team of physicists from UCLA, Wheaton College, the University of Iowa, and the Space Science Institute has resolved one of the mysteries that surrounds the origins of the aurora borealis.
Their research, "Laboratory measurements of the physics of auroral electron acceleration by Alfvén waves", is published in the journal Nature Communications.
Aurora Borealis Final Mystery of Origins
The Sun releases electrons and other charged particles as part of the solar wind. These particles then speed down the magnetic field and atmosphere of the Earth where they collide with oxygen and nitrogen molecules, activating them. The result: light that creates the beautiful aurora borealis.
However, as to how groups of electrons accelerate through the magnetic field during the last part of their journey at a speed of 45 miles per hour, remains a mystery to many scientists.
According to EurekAlert!, some theorize that electrons must have hitched a ride on a type of electromagnetic wave that travels along the magnetic field lines above the auroras, which is called the Alfvén waves. Although space-based research may have provided support for this theory, it does not completely answer the mystery because of the limitations of spacecraft measurements.
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Electrons Surfing
The recent study answers the mystery. The team reproduced the conditions on the auroral magnetosphere using instruments specially designed to launch Alfvén waves into a 20-meter-long chamber of the plasma device.
According to UCLA's news release, "This challenging experiment required a measurement of the very small population of electrons moving down the chamber at nearly the same speed as the Alfvén waves, numbering less than one in a thousand of the electrons in the plasma," said physics professor Troy Carter, the director of the UCLA Plasma Science and Technology Institute.
Gregory Howes, an associate professor of physics at the University of Iowa, added that measurements revealed that these electrons undergo a resonant acceleration through the electric field of the Alfvén wave, like surfing on ocean waves and being accelerated as it moves along with the wave.
In 1946, Lev Landau, a Russian physicist, called the "surfing" idea the Landau damping. His theory has finally been proven.
A Long Way to Go to Predict How Strong Each Geomagnetic Strong Will Be
Despite proving the Landay damping, the team believes that there is still a long way to go to be able to predict how strong each geomagnetic field will be, according to CNN.
Howes said in an email to CNN that predicting the intensity of geomagnetic storms remains an unsolved challenge as scientists have yet to establish the link between surfing electrons and Alfven waves about 10,000 miles above the Earth's surface.
He noted that to do that, scientists must learn how to predict the strength of those Alfven waves using spacecraft observations.
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