Are the northern lights making noise? Research tries to shed light on the mystery of the aurora
(CNN) – In the dead calm of a winter night on a remote Canadian stretch of the Alaska Highway – with no other soul in sight – the hiss of something echoed in the MacDonald Valley where Ryan Dickie had driven to photograph the Northern Lights.
It was the evening after a particularly active display of the famous sky phenomenon over Dickie’s house in northern British Columbia. The 36-year-old indigenous Dene photographer and conservationist from Canada’s Fort Nelson First Nation decided to go to a place far from any light pollution to film a similarly spectacular show in the sky.
But when he stepped outside into the frozen night to adjust his camera settings, it was the sound – not just the sight – that stopped him.
“If you live up here you hear stories that they (the northern lights) make a noise and when you whistle at them they get closer to the ground,” said Dickie. “My grandma told me a story as children growing up in the countryside near the Liard River about how the northern lights made clicks, like you would call your dog.”
But when Dickie finally heard it, it was different.
“It was a little weak at first, but it sounded almost like a piece of meat hitting a pan,” said Dickie.
Ears to heaven
Caused by solar flares on the sun’s surface, the northern lights – also known as aurora borealis or aurora – can appear in the Earth’s magnetic field as faint whitish or greenish cloud-like formations, or even as colored curtains and swirling explosions that erupt across the sky in green, pink, and purple. In places like Arctic Alaska, Arctic Canada, Northern Norway, Finnish Lapland, and other northern regions of the planet where they are regularly seen, there are countless reports of people hearing sounds in addition to the aurora.
Mamie Williams, a member of the Tlingit Tribe in Hoonah, Alaska, said her grandmothers used to tell her as a child to listen to the Northern Lights.
“It’s our ancestors who let us know, ‘We’ve crossed, but we’re still here with you,'” said Williams, a cultural interpreter who works with Alaska Native Voices.
Williams first heard the aurora borealis sing and crackle when she was 14 years old and said she has heard similar noises since then.
Once, when the sky was full of purples and greens, she said she even heard the drumming that accompanied the lights in the sky.
“The brighter they get, the more you hear,” said Williams.
Although reports like those by Dickie and Williams are not uncommon among both indigenous people and non-indigenous people who live where the northern lights are regularly seen, there has been little scientific research into the phenomenon.
The aurora borealis, captured by Dene photographer and conservationist Ryan Dickie, shines brightly over the Fort Nelson River in the far northeast of British Columbia, Canada.
Courtesy of @winterhawkstudios
“There have been years of anecdotal reports of people hearing a rustling or crackling sound,” said Donald Hampton, a research fellow at the University of Alaska Fairbanks Geophysical Institute who studies space physics and aurora and auroral interactions with the upper atmosphere.
“But if you think about it physically, there is no way you will get any noise from the aurora itself.”
That’s because the northern lights appear between 60 and 100 miles above the surface of the earth and it takes a few seconds to move a mile, Hampton said.
“If you’ve ever counted after a lightning strike, it takes five seconds for the sound to be a mile long,” he said. So if sounds were coming from the northern lights themselves, it would take five to 10 minutes to be heard on the ground.
Still, Hampton doesn’t rule out the theory that the northern lights may be responsible for the sound people claim to hear.
Shed light on a theory
For K. Laine, he first heard a sound accompanying the Aurora Borealis in 1990 when he was visiting the remote northern Finnish village of Saariselkä for a jazz festival.
Together with four friends, the professor emeritus of acoustics at Aalto University in Espoo, Finland, “suggested listening to the silence of Lapland,” he said. As the northern lights filled the sky above them, three people in his group heard no silence that night, but rather soft noises “like soap bubbles bursting,” said Laine.
“We really had to be very calm for two minutes and concentrate on listening,” he said.
It was an experience that never left him, Laine said, especially with all the stories from people who reported sounds related to the northern lights while no scientific research was being carried out on the phenomenon.
“That question mark was on my mind all the time,” said Laine, who has spent most of his career studying the phenomenon of noise. He has a theory about what people hear and associate with the northern lights.
“In the evening of a sunny day, the warm air begins to rise near the ground, while the ground temperature drops. Finally, the rise of warm air typically stops below a height of 100 meters,” said Laine. “This layer of warm air with colder air above and below is called the temperature inversion layer.”
Laine has spent decades recording the sounds using a three microphone setup and a VLF (very low frequency) loop antenna connected to a four channel digital recorder.
On clear evenings, Laine said, the inversion layer collects space charges – positive ones from the upper atmosphere and negative ones from the ground. The magnetic storm that is the cause of auroral lights triggers and sets these discharges in the inversion layer, creating audible sounds, he said.
Hampton said Laine’s theory was “out of the reach”.
“He’s assuming it’s something to do with electricity,” said Hampton. “A strong electric field could set up mechanisms that could cause air vibrations or small discharges that could burst or tear.”
Laine’s theory helped inspire a new civic science project launched this summer near Jyväskylä, Finland. For the first time, Hankasalmi Observatory volunteers will continuously record potential noises related to aurors 24 hours a day, using four microphones instead of Laine’s three.
Red and green auroras are shown over the Hankasalmi Observatory in Finland in 2015. Observatory volunteers will be continuously recording potential noises related to aurors this summer.
The project is partly funded by the European Union and 200 local volunteers.
The hope is that the four microphones – which can pick up the same sounds as the human ear – can pinpoint where the sounds are coming from, which will help prove or disprove Laine’s theory, said Arto Oksanen, president of the observatory.
“We’re trying to hear the same sound with three or four microphones a few feet apart,” he said. “By measuring the time delay for each recording, it is possible to calculate the three-dimensional position of the sound source – or at least the direction to the sound source.”
The combination of this result with the electromagnetic signal measured with a VLF antenna, according to Oksanen, also gives the distance to the sound source.
Oksanen, who said he was “open to anything and shoots,” admitted to being “a bit skeptical” that the northern lights make the sounds after spending hundreds of hours watching aurors without admitting them Listen.
“There have been so many stories from people who heard the noise, I don’t think they’re making it up,” he said. “But I don’t know if it’s real acoustic sounds. It should be very easy to record these days because everyone has a phone. So why aren’t there recordings?”
Compared to the portable setup that Laine has used to record, the observatory’s setup will be permanent and “will allow us to collect a lot more data,” Oksanen said. Adding an extra microphone “also gives more confidence and error analysis,” he said.
This green aurora arc in Muurame, Finland was captured in 2020 by Arto Oksanen, President of the Hankasalmi Observatory.
“A lot of universities and scientists don’t believe in the sounds and don’t even apply for funding for these recordings,” he said. “So maybe we can find something that no one has found yet.”
Not everyone needs a recording to be convinced that the sounds exist.
“It was definitely the sound I always heard,” said Dickie of the night along the Alaska Highway and the show in his sky – and in his ears – that he will never forget.
“I was sure it was the sound of the northern lights.”
Above: The aurora borealis ignites the early morning sky just before sunrise near Fort Nelson in northeast British Columbia, Canada. Courtesy of @winterhawkstudiosTerry Ward is a freelance writer based in Tampa, Florida.