- Some people, including Arctic explorers, have reported hearing sounds when they see the Northern Lights.
- An expert explains what can cause these rattling sounds: One theory suggests that they come from electrically charged particles that crackle in the Earth’s atmosphere.
It’s a question that has puzzled observers for centuries: Do the stunning green and crimson light displays from the aurora borealis make any noticeable sound?
Enchanted by the interaction between solar particles and gas molecules in the Earth’s atmosphere, the aurora generally occurs near the Earth’s poles, where the magnetic field is strongest. Reports that aurora is noisy, however, are rare – and were historically rejected by researchers.
But a Finnish study in 2016 finally claimed to have confirmed that the Northern Lights really produce sound that can be heard to the human ear. A recording made by one of the researchers involved in the study even claimed to have captured the sound of the captivating lights 230 feet (70 meters) above the ground.
Yet the mechanism behind the sound remains somewhat mysterious, just as the conditions are met for the sound to be heard. My recent research takes a look at historical reports on auroral sound to understand the methods of investigating this elusive phenomenon and the process of determining whether reported sounds were objective, illusory of imaginary.
People have said that the northern lights sound like rattling silk
Auroral noise was the subject of particularly lively debate in the early decades of the 20th century, when accounts from settlements across northern latitudes reported that sound sometimes accompanied the fascinating light screens in their skies.
Witnesses recounted a quiet, almost imperceptibly crackling, whispering or hissing noise during particularly violent northern lights performances. In the early 1930s, for example, personal testimonies began to flow into The Shetland News, the weekly magazine on the subarctic Shetland Islands that likened the sound of the Northern Lights to “rattling silk” or “two planks meeting flat roads.”
These narratives were confirmed by similar testimonies from northern Canada and Norway. Yet the scientific community was less than convinced, especially given the very few Western explorers who claimed to have heard the elusive sounds themselves.
The credibility of auroral noise reports from this time was closely linked to altitude measurements of the Northern Lights. It was considered that only those screens that fell low into the Earth’s atmosphere would be able to transmit sound that could be heard by the human ear.
The problem here was that the results recorded during the Second International Polar Year 1932 to 1933 found that auroras most often took place 100 miles above the Earth and very rarely below 80 miles. This suggested that it would be impossible for noticeable sound from the lights to be transmitted to the earth’s surface.
In view of these findings, eminent physicists and meteorologists remained skeptical and rejected accounts of auroral sound and very low auroras such as folklore stories or auditory illusions.
Sir Oliver Lodge, the British physicist involved in the development of radio technology, commented that auroral sound can be a psychological phenomenon due to the liveliness of aurora’s appearance – just as meteors sometimes produce a hoarse sound in the brain. Similarly, meteorologist George Clark Simpson argued that the appearance of low auroras was probably an optical illusion caused by low cloud disturbance.
The sound of the aurora can come from the electricity in the Earth’s atmosphere
Nevertheless, the leading auroral researcher of the 20th century, Carl Størmer, published accounts written by two of his assistants who claimed to have heard the aurora, which added some legitimacy to the large amount of personal reports.
Størmer’s assistant Hans Jelstrup said he had heard a “very curious faint whistling sound, clearly undulating, which seemed to follow exactly the vibrations of the aurora,” while his other assistant, Mr. Tjönn, experienced a sound like “burning grass or spray.” As convincing as these last two testimonies may have been, they still did not suggest a mechanism by which auroral sound could work.
The answer to this enduring mystery, which has subsequently garnered the most support, was first tentatively proposed in 1923 by Clarence Chant, a well-known Canadian astronomer. He argued that the motion of the Northern Lights changes the Earth’s magnetic field and causes changes in the electrification of the atmosphere, even at a considerable distance.
This electrification produces a crackling sound much closer to the earth’s surface when it encounters objects on the earth, just like the sound of static. This can take place on the observer’s clothes or glasses or possibly in surrounding objects, including spruce trees or cladding of buildings.
Chant’s theory correlates well with many accounts of auroral sound and is also occasionally supported by reports of the odor of ozone – which allegedly carries a metallic odor resembling an electric spark – during Northern Lights displays.
Yet Chant’s paper went largely unnoticed in the 1920s and did not receive recognition until the 1970s, when two aural physicists visited the historical evidence. Chant’s theory is widely accepted by scientists today, although there is still debate about how exactly the mechanism for producing sound works.
It is clear that the aurora in rare cases makes sounds audible to the human ear. The eerie reports of crackling, hissing and buzzing sounds that accompany the lights describe an objectively audible experience – nothing illusory or imagined.
To hear the northern lights, go to a mountain top
If you want to hear the Northern Lights yourself, you may need to spend a significant amount of time in the polar regions, given that the sound phenomenon only shows up in 5% of violent auroral performances. It is also heard most on top of mountains, surrounded by only a few buildings – so it is not a particularly accessible experience.
In recent years, the sound of the aurora has nevertheless been studied for its aesthetic value, inspiring musical compositions and laid the foundation for new ways of interacting with its electromagnetic signals.
The Latvian composer Eriks Ešenvalds has used magazine excerpts from the American explorer Charles Hall and the Norwegian statesman Fridjtof Nansen – who both claimed to have heard the northern lights – in his music. Ešenvald’s composition, Northern Lights, intertwines these reports with the only known Latvian folk song that tells of the auroral sound phenomenon, sung by a tenor solo.
Or you can also listen to the radio signals from the Northern Lights at home. In 2020, a BBC 3 radio program switched very low frequency radio recordings of the aurora to the audible spectrum. While not the same as perceiving audible sounds from the Northern Lights personally on a snow-capped mountain peak, these radio frequencies provide a great sense of the aurora’s transient, fleeting and dynamic nature.