Aurora Mystery Solved: Strange, Sudden Bursts are Caused by Swirling, Charged Particles

An auroral mystery has finally been solved. Scientists have found that sudden aurora bursts are caused by swirling, charged particles and have learned a bit more about the spectacle known as auroral breakup.

For years, scientists have contemplated what triggers the formation of auroral substorms and the sudden bursts of brightness. Now, researchers have overthrown existing theories about the mechanism behind the phenomenon.

Auroras originate from plasma from the sun, known as the solar wind. In the 1970s, scientists discovered that when this plasma approaches the Earth together with magnetic fields, it triggers a change in the Earth's magnetic field lines on the dayside, and then on the night side. This information, though, couldn't explain how the fluttering lights emerge in the sky.

"Previous theories tried to explain individual mechanisms like the reconnection of the magnetic field lines and the diversion of electrical currents, but there were contradictions when trying to explain the phenomena in its entirety," said Yusuke Ebihara, one of the researchers, in a news release. "What we needed all along was to look at the bigger picture."

In this case, the researchers found that hot charged particles, or plasmas, gather in near-Earth space just above the upper atmosphere of the polar region when magnetic field lines reconnect in space. This causes the plasma to rotate, creating a sudden electrical current above the polar region. This, in turn, causes electric current overflows near the bright aurora, making the plasma rotate and discharge extra electricity. This gives rise to the "surge," which are the very bright spots of light that characterize substorms.

The findings reveal a bit more about the aurora, and shows how the bursts emerge.

The findings are published in the Journal of Geophysical Research: Space Physics.

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