In a new study, researchers say a purple light in the northern sky doesn’t appear to be an aurora, but they can’t quite explain what causes it.
Researchers say the light, referred to as STEVE (Strong Thermal Emission Velocity Enhancement), has been photographed for decades by amateurs snapping photos of the Northern Lights, but has only been under scientific study since 2016.
The light appears in the sky as a purple “stream” rather than the green glow typically created by the aurora.
According to the American Geophysical Union, using data from a March 2008 report of the STEVE light, researchers found the light was created by a different atmospheric process than standard auroras, but they are still working to better understand the process.
“Our main conclusion is that STEVE is not an aurora,” said Bea Gallardo-Lacourt, lead researcher and a space physicist at the University of Calgary in Canada. “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.”
(Photo from Ryan Sault/American Geophysical Union)