If you’ve ever been lucky enough to see the Northern Lights, you may have noticed a whitish-grey patch that can be seen amidst the dance of colors across the sky. Now, for the first time, researchers at the University of Calgary may have discovered what it could be.
Published on Dec 30th in Nature Communications, Calgary researchers explored what they describe as a “structured continuum emission” connected to the northern lights. The team says this type of light spreads across a wide range of colors, but unlike regular light, it has some visible patterns or shapes.
Named for the Roman goddess of dawn, the aurora borealis are spectacular natural light shows produced by solar energy and fueled by electrically charged particles trapped in Earth’s magnetic field. While beautiful, they can also interfere with various communication systems and other technologies.
Dr. Emma Spanswick, PhD, lead author of a recent paper detailing the new findings, says the patch has been referenced in papers before but has never been explained.
“You’d see this dynamic green aurora, you’d see some of the red aurora in the background and, all of a sudden, you’d see this structured–almost like a patch-grey-toned or white toned-emission connected to the aurora,” says Spanswick.
In the past, most astronomers have been left scratching their heads. But Spanswick and her team, after searching for what could cause this effect, claimed it’s “most certainly a heat source” and suggested the aurora borealis is more complex than previously thought.
Spanswick says that the rise in the appearance of advanced cameras in recent decades allowed amateur photographers and astronomers to see the true essence of the night sky in full color. “Everyone has noticed the advancement in digital photography. Your cellphone can now take pictures of the aurora,” she says. “That has flowed to the commercial sensor market now.”
“Those types of sensors can now be found in more commercial, more robust sensors that we would use in science,” Spanswick says.
The team’s research was inspired by a renewed curiosity involving continuum emission, especially after the discovery of the stunning, glowing purple ribbon of light known as the Strong Thermal Emission Velocity Enhancement, or STEVE.
“There are similarities between what we’re seeing now and STEVE,” explains Spanswick. “STEVE manifests itself as this mauve or grey-toned structure.”
“To be honest, the elevation of the spectrum between the two is very similar but this, because of its association with dynamic aurora, it’s almost embedded in the aurora,” Spanswick added. “It’s harder to pick out if you were to look at it, whereas STEVE is separate from the aurora – a big band crossing the sky.”
Marc Dantonio, founder of Sky Tour Live Stream Observatories, told The Debrief that the discovery of STEVE “began to unveil the secrets of what was thought to be a previously well-understood phenomenon that occurs every night in our northern and southern skies.”
“In a similar approach, this strong white continuum emission that we’re seeing represents yet another process going on in the skies overhead.”
“As it turns out, this phenomenon indicates an area where the atmosphere is locally heated to some extent, and this has been labeled a ‘heat source,'” says Dantonio.
Spanswick offered congratulations to her team for their recent discovery, which included three UCalgary students and intern undergraduate Josh Houghton, who performed a significant amount of the analysis for this research.
“He’s had one heck of an internship experience,” Spanswick says.
Chrissy Newton is a PR professional and founder of VOCAB Communications. She hosts the Rebelliously Curious podcast, which can be found on The Debrief’s YouTube Channel. Follow her on X: @ChrissyNewton and at chrissynewton.com.