The ominous red presence of the Northern Lights in the skies of continental Europe was seen as a harbinger of war. In the weeks before the French Revolution a bright red Aurora was seen over Scotland and England with reports of the sound of mighty battles being heard, intriguingly raising the question of whether the Northern Lights made a noise.
One who took the subject seriously was the first man to photograph them in October 1882, Danish astrophysicist, Sophus Tromhult, doubtless inspired by his father, Johan, who claimed to have heard them three times between 1838 and 1843. He likened their sound to the quiet but rapid rubbing together of two pieces of paper. Despite a career spent observing the lights, Sophus never heard them.
In the 1930s The Shetland News was inundated with reports, some contemporary, others historic, of sounds emanating from the Northern Lights. One such, published on May 20, 1933, from Peter Hutchison claimed that “on clear and frosty nights about thirty years ago the “pretty dancers”…would flit and fro, making a noise as if two planks had met flat ways – not a sharp crack but a dull sound, loud enough for anyone to hear. We boys got so used to this that we never heeded the noise when the pretty dancers came out to clap their hands”. These reports were corroborated by other witnesses in Canada and Norway.
Persistent reports of noises emanating from aurorae were discounted by the scientific community, the witnesses having no rigorous scientific training and the altitude at which they occurred being beyond the range of human hearing. This scepticism began to change when the eminent auroral scientist, Carl Størmer, published the experiences of two of his assistants who described hearing “a very curious faint whistling sound, distinctly undulatory, which seemed to follow exactly the vibrations of the aurora” and a sound like “burning grass or spray”.
A hundred years ago a paper published by Clarence Chant in The Journal of the Royal Astronomical Society of Canada[1] (September 1923) provided the now accepted explanation behind the sounds produced by aurorae, although there is still some debate as to how the mechanism that produces the sound operates. The motion of the Northern Lights, he argued, altered the Earth’s magnetic fields, inducing a change in the electrification of the atmosphere which, in turn, generated a crackling sound much closer to the Earth’s surface when it met objects on the ground, much like static. Chant’s theory lay neglected until the 1970s.
The chances of hearing an aurora were thought to be considerably lower than seeing one, some experts suggesting that the aural phenomenon only presents itself in five per cent of violent auroral displays. However, some recent research by Professor Emeritus Laine of Aalto University suggests that they might be more common than originally thought, citing a remarkable correlation between geomagnetic fluctuations and auroral sounds. Even more astonishingly he claims that that many of what he termed as possible auroral sounds occur even in the absence of visible Northern Lights, in other words that it is possible to hear them even if you cannot see them, and that absent a visual accompaniment the sounds made by the Northern Lights might easily be passed off as something more mundane.
To hear a version of them, check out a Radio 3 programme[2] in the Between The Ears series, first aired on Boxing Day, 2020, which remapped very low frequency radio recordings of aurorae to levels audible to the human ear. Although not quite the same as the real thing, it shows that the Northern Lights should be reclassified as one of nature’s finest Son et Lumiere shows.
[1] https://adsabs.harvard.edu/pdf/1923JRASC..17..273C
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