STEVEs are not auroras after all, study reports

New research into Strong Thermal Emission Velocity Enhancements show that they are not auroras

New research on unique atmospheric effects known as Strong Thermal Emission Velocity Enhancements (STEVEs) show that they are not auroras, but rather a never-before-recorded atmospheric phenomenon.

Researchers first began to analyze the cosmic lights a few years ago when citizens posted images of them to a Facebook group known as Alberta Aurora Chasers.

Though the bands look like typical auroras, they do not blanket the night sky. Rather, they are narrow and shoot up in colorful ribbons. That unique property is what drew scientists to them.

Auroras occur when electrons and protons from Earth’s magnetosphere rain down onto the ionosphere. That then shoots off a range of colors, including green, red, and blue.

While STEVEs look like auroras, they have key differences that set them apart. Not only do they appear as ribbons with purple and white hues, but they also run from east to west, and sit closer to the equator than auroras. In addition, though auroras are visible every night in their regions, STEVEs can only be viewed a few times each year.

Even so, despite the differences researchers still believed that STEVEs came about through the same processes that create auroras. The new research refutes that.

“Our main conclusion is that STEVE is not an aurora,” said lead author Bea Gallardo-Lacourt, a researcher from the University of Calgary, according to Gizmodo. “So right now, we know very little about it. And that’s the cool thing, because this has been known by photographers for decades. But for the scientists, it’s completely unknown.”

To learn more about the phenomena, the team in the study used a network of ground-based All-Sky Images to analyze the light from a STEVE event to see if the light came about from a known or new process.

That revealed no traces of particle precipitation, a finding that suggests that STEVEs are not auroras. Their light likely comes about from a brand new mechanism that is not on record.

Researchers plan to further study the events in the near future.

“This is a light display that we can observe over thousands of kilometers from the ground,” said Liz MacDonald, a space scientist at NASA’s Goddard Space Flight Center who was not involved in the research, according to USA Today. “It corresponds to something happening way out in space. Gathering more data points on STEVE will help us understand more about its behavior and its influence on space weather.”

This new research is published in the Geophysical Research Letters.

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