One of the most fascinating natural experiences humans have had for centuries is the beautiful green and colourful auroras visible in the polar areas. Auroras are dancing green and colourful wavy patterns of light visible in the night sky of areas closer to the earth’s poles. The auroras have inspired an array of scientific research alongside numerous mythical legends. One of the highly debated phenomena associated with auroras is the local people’s claims of hearing lights while the auroras danced in the sky. They observed that the rhythm of the discernible whooshing, whizzing, or crackling sounds matched that of the colourful lights in the sky.
According to historical research conducted by Fiona Amery of the Department of History and Philosophy of Science, the University of Cambridge, the recorded personal testimonies of hearing such sounds go back to the early 1930s. Among the records investigated by the researcher, are the published testimonies in The Shetland News, a weekly newspaper from the subarctic Shetland Islands. The flooded testimonies described the sounds by comparing them to silk rustling or “two planks meeting flatways.” Such testimonies resonated in other areas as well such as northern Canada and Norway where the northern lights were visible.
When scientists tried to look into the matter, they conducted various experiments testing the properties exhibited by the auroras. The research was accelerated at the time because of the Second International Polar Year, a year observed by meteorological scientists with research foci on the polar areas. When scientists measured the heights of the auroras, which are basically disturbances in the earth’s magnetosphere caused by the solar wind, they found that the phenomenon rarely occurred below a height less than 80 km. To scientists, this was an indication that it was almost impossible for a discernible sound to be transmitted from the lights and reach people on the earth. As a result, well-known physicists and meteorologists were dismissive of the claims of hearing sounds from auroras. A British physicist Oliver Lodge even suggested that such experiences might be a psychological phenomenon while another meteorologist argued that low auroras were likely an optical illusion.
But when a Canadian astronomer Clarence Chant presented his own theory of auroral sounds he garnered support as he had given an explanation to people’s experiences. According to Chant, similar to the crackling sounds made by our clothes when we take them off — which is a result of electrification, the changes in the electrification of the atmosphere caused by the auroras can create sounds that can faintly be heard even on the surface. Chant’s theory went largely unnoticed only to be discovered later. The mechanism proposed in his theory though is still debated.
The dismissals of auroral sounds were finally overshadowed by a final confirmation in 2016 that auroral lights indeed produce sounds that are audible to the human ear. According to the new explanation, separate layers of warm and cold air are created in the calm polar regions and they do not mix well. The below layer traps negatively charged particles and the top layer traps positively charged particles. When a geomagnetic storm hits, creating auroras, it breaks the layered lid of charges releasing the accumulated opposite charge and creating sounds.
Read all the Latest News, Breaking News and Coronavirus News here. Follow us on Facebook, Twitter and Telegram.