Cackle of Aurora Borealis Is No 'Malfunction' but a Reality, Researchers Claim

The visual spectacle of the Northern light is a popular phenomenon worldwide, but very few people know about the "sounds" it brings. The Northern light, also known as the aurora borealis, has been reported for centuries by many native populations as making sounds, according to Popular Mechanics. For different groups, it meant different things. The Inuit people of Greenland considered it to be a pathway to heaven. They believed that amongst the multicolored hues, the departed souls are enjoying themselves. For Scandinavia's Sami people, the Northern Lights were a symbol of respect and fear. All of these people may have differed in views, but held common ground when it came to the unique sound produced by it.

Do the Northern Lights make sound?

Danish explorer Knud Rasmussen claimed the locals in Greenland believe these sounds are made due to souls running across the "frost-hardened snow of the heavens." Scientists disregard this assertion and are also sure that the aurora borealis itself cannot produce the speculated sound, which seems to crackle, pop, and rustle. They asserted that Northern Lights happen 60 to 200 miles in the ionosphere, where the air is so thin that it cannot carry sound waves.

Even if the aurora manages to produce a sound, it would likely vanish by the time it reaches Earth. For a long time, experts believed that native people who claimed to hear the sound were just imagining it. They thought that for such people, a sort of malfunction occurred in the senses or cognitive system, which led them to hear those sounds. 

Proof of the Sound

The 'imagination' claim fell apart when a team of experts recorded these sounds for the world to hear, according to Live Science. The researchers claimed in a study that the sound came with the northern lights 70 meters above ground level. In the 20th century, two assistants of astronomers claimed to have heard those sounds, as reported by the BBC. These people possibly had no fascination with the northern lights; hence, for them to conjure up sounds did not seem likely. The 'proof' in 2016 validated that the phenomenon was accompanied by sounds audible to human ears. Since then, scientists have been in pursuit of the origin of these elusive sounds. 

Mystery Resolved

The answer to this mystery was first suggested by Clarence Chant, a well-known Canadian astronomer, in 1923. He claimed that the motion exhibited by the aurora borealis altered Earth's magnetic field, facilitating changes in the electrification of the atmosphere. This electrification could produce sound when it interacts with objects on the surface. These objects could be the observer's clothes or fir trees found in the cold sites. The sound supposedly produced during this process is static, which aligns with the crackle claim associated with the mysterious sounds. 

The same hypothesis was put forward by Unto Kalervo Laine, a professor at Aalto University in Finland. He claimed that during the formation of Northern Lights, an inversion layer containing warm air rising from the Earth is created. This layer carries negative charges underneath positive charges. The layer gets disrupted when magnetic field pulses occur during the event, resulting in crackling and popping sounds. He explains the hypothesis in detail within his 2016 paper.