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Thursday, August 23, 2018, 7:05 pm – A mystery of the night sky only became stranger and more mysterious. The purple and green glowing arcs, which some & # 39; STEVE & # 39; call, are apparently not aurora's, but something completely different – and unknown!
Aurora hunters have been observing a strange phenomenon in the air for years.
Thin glowing arcs of light with purple and green light have been seen and photographed, stretching across the sky, usually far south of any other aurora activity that may occur at that time.
In this photo, taken by Alberta Aurora-photographer Theresa and Darlene Tanner on July 17, 2018, the diffuse green electron aurora is shown at the bottom left, and two swaths of another phenomenon on the right, that proton arch & # 39; is called, "sub-auroral arc & # 39 ;, or more recently," & # 39; STEVE & # 39 ;. Credit: Team Tanner Photography
It was originally thought to be an aurora in itself, but a new study of these glowing arcs – the name & # 39; STEVE & # 39; is mentioned – says that they are not a kind of known aurora at all.
"Our main conclusion is that STEVE is not aurora," said Bea Gallardo-Lacourt, the physicist at the University of Calgary who led the study, now published in the journal Geophysical Research Letters, according to the American Geophysical Union (AGU). "So at the moment we know very little about it."
"And that's nice," she added, "because this has been known to photographers for decades, but it's completely unknown to the scientists."
By examining a specific specimen of this phenomenon, Gallardo-Lacourt and her colleagues from 28 March 2008 have made images of the THEMIS array of all-sky cameras from the University of Calgary, with at the same time particle data collected from NOAA's Polar Orbiting Ambient Satellite 17 (POES-17).
View below: The THEMIS network of all-sky cameras has captured this amazing view of aurora on April 20, 2018.
Although the timing of STEVE's THEMIS photo's corresponded to the timing of POES-17 data, the satellite showed that were no charged particles rains from space at the location where STEVE took place.
"With Steve what's happening, we can not find evidence of that particle precipitation, so it looks like the energy that causes the light to come from somewhere else," Eric Donovan, a co-author of Gallardo-Lacourt & # 39; s study from the University of Calgary's Auroral Imaging Group, told CBC News.
The next step for the research group is to investigate more examples of STEVE to determine its origins.
Does it originate from the magnetosphere, as other auroras do, but by a still-or-yet-undiscovered process, or is it caused by particles that emit much closer to the ground – in the ionosphere, below where the POES-17 satellite would they have discovered?
The aurora's that are part of the northern lights and the southern light – Aurora Borealis and Aurora Australis respectively – are caused by charged particles that arrive on the earth's wind, get stuck in the earth's magnetic field and then flow down into the upper layers of the atmosphere. There, these high-energy particles store in molecules of oxygen and nitrogen and they move over a part of their energy. When the molecules that dump excess energy, they do so as light. This is represented as ribbons of pink, green, red, blue and purple that can extend over the entire night sky.
This colorful view of the northern lights was captured on May 28, 2017 by the Tanners from the center of Alberta. Credit: Team Tanner Photography
If the particles are small negatively charged electrons, we see colorful bands and swirls of pink, green, red, blue and purple. However, if the particles are more massive, positively charged protons, we do not tend to see anything unless we have a special camera. The light that the molecules emit when a & # 39; proton aurora & # 39; is located in the ultraviolet spectrum, which is invisible to the human eye.
According to spacecraft predictor Dr. Tamitha Skov, aurora-photographers saw thin bright bows of purple and green that stretched across the sky, in contrast to everything they had seen from the typical aurora, they called them protonbows & # 39 ;.
While members of the community knew they would not be real proton aurora, since they were easily visible, Skov says that the arches share certain characteristics of timing and location with invisible proton aurora & # 39; s.
The name thus acted as a placeholder within the community until they could be correctly identified. Another name used by the community is sub-auroral arc & # 39 ;, which was seen as a more accurate description, without relating it to a particular aurora phenomenon.
At the end of 2016, members of the Alberta Aurora Chasers met Donovan at an annual conference and they showed him images of these long, thin, purple arches in the air.
As other scientists had done in the past, he concluded that they were not a proton aurora. Because nobody in the group knew exactly what they were, they gave the phenomenon a humorous nickname – Steve.
According to the Aurorasaurus blog:
Why Steve? Well, this is a reference to the popular children's film About the hedge where one of the characters is not sure what he is looking at and it randomly names Steve.
Since then, the name has become something of an unmanageable (but possibly accurate) & # 39; backronym & # 39; – STEVE, or Sudden Thermal Emission Velocity Enhancement.
Sources: AGU | CBC | University of Calgary | Aurorasaurus | With files from The Weather Network
RELATED: SEE THIS SPOTTED AURORA ABOUT ALIX, ALBERTA CAUGHT ON CAMERA BY #TEAMTANNER
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