STEVE, the purple and white lights that have caught the attention of scientists a few years ago, might be a new type of celestial phenomenon.an
A new study published recently suggests that the stream of lights that appear in the night sky might look like an aurora. However, it is actually a different glowing light in the night sky dubbed as "skyglow."
"Our main conclusion is that STEVE is not an aurora," stated Bea Gallardo-Lacourt, a space physicist and author of the study published in Geophysical Research Letters. "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."
STEVE, which stands for Strong Thermal Emission Velocity Enhancement, was first observed by a group of citizen scientists who took photos of the light show in Canada. Unlike an aurora, this new phenomenon produces thin, bright ribbons of green, white, and purple lights that appear only a few times a year and appear much closer to the equator.
Researchers, who became aware of the phenomenon in 2016, partnered with the Alberta Aurora Chasers and other citizen photographers to combine the dates and times that STEVE appeared in the night sky. They also made use of satellites to observe the Earth's magnetic field to figure out what is causing the unusual light show.
Aurora Vs. STEVE
Aurora, also known as the northern and southern lights, form when the charged particles from the sun travel down the magnetic field lines at the poles and interact with the gases of the planet's atmosphere. These create colorful lights that are visible every night if viewing conditions are right.
Meanwhile, researchers used a satellite equipped with an instrument that measures charged particle in the ionosphere to determine whether STEVE is caused by the same mechanism as the auroras. However, the satellite detected no charged particles raining down to the ionosphere during the unusual phenomenon.
"With STEVE what's happening is we can't find evidence of that particle precipitation, so it seems like the energy that's causing the light is coming from somewhere else," Eric Donovan, co-author of the study, told CBC. "Interestingly, its skyglow could be generated by a new and fundamentally different mechanism in the ionosphere."
Studying STEVE could help scientists further understand the upper atmosphere and the processes that create the enchanting light shows that appear in the night sky.