Is it true that the northern lights make noises?—Jeremy Evelyn, via email
Maybe. There’s some evidence that the aurora borealis is associated with sound, says Robert Rankin, a professor in the department of physics at the University of Alberta. But “some evidence” doesn’t make it true. “There’s also evidence for UFOs,” says Rankin.
There are plenty of anecdotal reports. People who witness the aurora often also claim to hear crackling, hissing, or rustling. And given how the northern lights are produced, it seems like they should be loud. A quick breakdown: sometimes the sun, which is always flinging material into space, sends a massive burst of the stuff towards Earth. This one billion tonnes of matter hits our magnetic field, where it can cause a geomagnetic storm—plus, on occasion, a wicked light show, when the particles flow into the atmosphere. Colourful, yes. But noisy? As Rankin points out, “Does the blue sky make a sound?”
In 2016, Finnish scientists presented results from their research on the acoustics of auroras after recording hundreds of “auroral sound events” over southern Finland. Their explanation? The sounds came from the geomagnetic storms’ negative electrical charges interacting with positive electrical charges, to create loud-enough-to-hear magnetic pulses.
This exciting discovery was announced pretty much everywhere. Everywhere except “high-quality refereed journals,” says Mark Conde, a professor at the Geophysical Institute at the University of Alaska Fairbanks. Sad trombone: this makes it very difficult to evaluate the reliability of the claim. “It’s clear that they recorded something,” says Conde. “But the association with the aurora is less well established.”
Still, all those witnesses must be hearing something. “If you stand out in the dead of winter on the tundra…you might hear things,” says Rankin. “It could be the wind. It could be crackling in the currents of air.” Or it could be the northern lights. “I can’t rule it out,” he admits. “Nothing is impossible.”
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