The New Kind of Aurora called STEVE is Not actually an Aurora

The New Kind of Aurora called STEVE is Not actually an Aurora

A recent study explains that the Strong Thermal Emission Velocity Enhancement (STEVE) is a one-of-its-kind celestial event which shouldn’t be confused with auroras.

The Northern and Southern Lights have been offering dazzling scenes to the people of the Arctic Circle and the Southern tip of Chile, respectively. Both these auroras have existed for centuries and travelers from different parts of the world visit these places annually to see these amazing displays of nature. A lot of superstitions were associated with these auroras before scientists found a logical explanation for their existence. This colorful display in the night sky is caused due to an interaction between the Earth’s magnetic field and the charged solar particles.

In 2016, the scientific community was notified about another similar phenomenon called ‘STEVE’. On 25th July, a thin streak of purple light spread over the night sky of Northern Canada. This arc-shaped light seemed to have stretched for hundreds of miles in space. This strengthened the claims of a lot of photographers who have been posting such images for decades. At that time, the scientists did notice that the light from STEVE is slightly different from the one we get with typical auroras but they didn’t know the scientific reasons which lead to this display. The fact that it coincided with the Aurora Borealis added to the mystery of these lights.

The Alberta Aurora Chasers (AAC) played an important role in getting STEVE noticed by the scientists. It was a Facebook group which occasionally captured thin streams of purple and white light in the night sky while they were photographing the Northern Lights. Unlike auroras, STEVE was visible only when the conditions were ideal and you needed to be at high latitudes to view it. At first, the photographers thought that these light ribbons are made up of excited protons but this idea faded away pretty quickly because normal cameras cannot record the wavelengths of such protons. This gave birth to a mystery which continued to escalate till 2016 when scientists finally decided to find a reasonable explanation for these lights.


According to a new study published in the journal ‘Geophysical Research Letters’, STEVE is an entirely new celestial phenomenon and it is surely not an aurora. The researchers from the Department of Atmospheric and Oceanic Sciences at the University of California and the Department of Physics and Astronomy from the University of Calgary collaboratively analyzed an occurrence of STEVE, which took place on the 28th March 2008, to look into its formation technique. The results showed that a completely different atmospheric process gives birth to the STEVE. Bea Gallardo-Lacourt, the Lead Author of the study who is a Space Scientist at the University of Calgary, talked about their findings and said,

Our main conclusion is that STEVE is not an aurora. 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.”

The researchers used the data gathered for a previous research as well to incorporate as much information in their study as possible. According to that study, a stream of fast-moving ions and electrons was detected in the regions where STEVE was observed. However, there was nothing conclusive whether it played a role in its formation or not. Gallardo-Lacourt decided to investigate the mysterious origin of STEVE and began her research by making use of the images taken from ground-based cameras.

She combined these pictures with the data from the Polar Orbiting Environmental Satellite 17 (POES-17) of NOAA as it was flying directly over the ground-based cameras during the STEVE event. The satellite revealed that there were no charged particles there at that time which led the researchers to the conclusion that the formation mechanism of auroras is different from these lights.

The satellite from the European Space Agency found that a ridiculously hot gas was slicing through the atmosphere there when it went right through STEVE in 2016. Likewise, the temperature of the air inside STEVE was 3000o C more than the air on each side. Similarly, it moved 500 times faster than the surrounding companion. Although STEVE is not an aurora, the uncertainty about its origin is still there. Joe Borovsky, a Space Scientist at the Space Science Institute in New Mexico, summed up the situation perfectly by saying,

This is really interesting because we haven’t figured it out and when you get a new problem, it’s always exciting. It’s like you think you know everything and it turns out you don’t.

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