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L.E.Ds Displays

Within the First International Polar Year expedition reports, Danish schoolteacher Sophus Tromholt and Maj. Henry Dawson focused research on auroral sound. In 1882, Tromholt established a base at Kautokeino, a Norwegian village close to the Finnish–Norwegian border. (Image credit:The Royal Society Journal of the History of Science/CC By 4.0)

Auroral noise was the subject of particularly lively debate in the first decades of the 20th century, when accounts from settlements across northern latitudes reported that sound sometimes accompanied the mesmerizing light displays in their skies.

Witnesses told of a quiet, almost imperceptible crackling, whooshing or whizzing noise during particularly violent northern lights displays. In the early 1930s, for instance, personal testimonies started flooding into The Shetland News, the weekly newspaper of the subarctic Shetland Islands, likening the sound of the northern lights to “rustling silk” or “two planks meeting flat ways.”

These tales were corroborated by similar testimony from northern Canada and Norway. Yet the scientific community was less than convinced, especially considering very few western explorers claimed to have heard the elusive noises themselves.

The credibility of auroral noise reports from this time was intimately tied to altitude measurements of the northern lights. It was considered that only those displays that descended low into the Earth’s atmosphere would be able to transmit sound which could be heard by the human ear.

The problem here was that results recorded during the Second International Polar Year of 1932-3 found aurorae most commonly took place 100 km above Earth, and very rarely below 80 km. This suggested it would be impossible for discernible sound from the lights to be transmitted to the Earth’s surface.