A ground-based observation facility tasked with recording the glow of the Northern Lights has captured images of an inexplicable pale gray glow amid the green and red streaks, providing researchers with new details about the mystery.
Although the bright intrusion itself has already been observed by observers of the Far North skies, no one has had a good explanation for its appearance.
Using the new spectral data, a team of researchers led by scientists at the University of Calgary in Canada may finally have a solution in the chemistry of the sky, comparing the white- and gray-bleached islands to the recently described meteorological oddity with THE relatively fanciful name ‘STEVE’.
“You would see this dynamic green aurora, you would see some of the red aurora in the background, and all of a sudden you would see this structured emission – almost like a spot – connected to the gray or white tones. dawn,” said Emma Spanswick, physicist at the University of Calgary.
“So any scientist’s first response is, ‘Well, what is it?'”
For the most part, the Sun retains its swirling soup of charged particles contained by gravity and a tangled web of magnetic fields. From time to time the forces align and see tiny amounts of plasma spurting freely in our direction.
Earth magnetic cage directs most of this energetic rain towards space, but in extreme cases a fraction of solar particles collide with the atmospheremaking its molecules glow in a rich palette of colors defined by their elemental composition and concentration.
While green and pink hues are expected in these luminescent displays, like the glow produced by oxygen and nitrogen at different altitudes, occasional splashes of white and gray have no simple explanation.
The aurora isn’t the only sight in town, however. Our planet’s atmosphere can shed light on other energetic processes, some a little more complex than others. Ordinary sunlight can cause molecules to disintegrate and recombine, for example by casting a faint visible light into the Earth’s shadow. known as night glow.
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Several years ago, a gray-purple ray of light, affectionately named Steve by aurora enthusiasts (retrospectively transformed into an acronym for Significant improvement in thermal emission speed), presented physicists with a mystery to solve.
Possessing a continuum of wavelengths that mixed to form shades of white and gray, STEVE’s structure and color distinguished it from conventional auroras. While the researchers keep moving forward To determine what is behind this unusual weather phenomenon, it is assumed that the faint reflections of the glow somewhat resemble a nighttime glow, the result of some sort of chemical rearrangement.
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“There are similarities between what we are seeing now and STEVE,” said Spanswick. “STEVE manifests itself through this structure with mauve or gray tones.
“To be honest, the spectrum rise between the two is very similar but, because of its association with dynamic auroras, it’s almost integrated into the aurora. It’s harder to distinguish if you look at it, so that STEVE is separated from the dawn – a big band crossing the sky.
Fortunately, researchers don’t need to squint into the sky night after night in hopes of spotting unusual blemishes in the aurora. The recently deployed high-resolution sky imaging observatory, called the Transition Region Explorer provides a record of aurora in color profiles calibrated to provide reliable spectral data, allowing the research team to analyze the mixture of wavelengths making up white light for clues about its production.
The researchers determined that the spots range in size from tens to several hundred kilometers, appear within active auroras, and are likely caused by something in the display releasing heat that, in turn, triggers chemical reactions capable of emitting a continuum of electromagnetic wavelengths.
What exactly breaks down and recombines to glow is only hypothetical at this point, but the whole process could represent a new chain of events tangentially linked to the aurora.
Modeling the layers of the atmosphere in laboratory experiments and collecting more examples of mysterious white patches of light could add vital details and new complexities to the sky’s greatest show.
This research was published in Natural communications.