Sound engineer Unto Laine from Aalto University in Finland has attempted to capture the strange sounds emanating from the sky on a night when a coronal mass ejection (CME) dramatically “landed” from the Earth’s magnetosphere.
CME events ignite the Earth’s sky with colorful auroras.
CME events typically follow geomagnetic storms (solar storms), which are streams of high-energy plasma. When they collide with the Earth’s magnetosphere, particles from the solar wind are accelerated along magnetic field lines to high latitudes, “raining” down into the upper atmosphere and interacting with particles in the air, creating stunning auroras.
The strange sounds, reminiscent of crackling and popping from the sky, sometimes resembling cracking or colliding noises, were recorded using special equipment set up near the village of Fiskars, Finland.
The data was cross-referenced with geomagnetic activity recorded by the Finnish Meteorological Institute and compared with other sound data to filter out noise. Ultimately, they identified about 60 strange sounds associated with changes in the Earth’s magnetic field with 90% accuracy.
Notably, these are sounds that the human ear can fully hear.
“These sounds are much more common than people think, but when they hear them without seeing the auroras, they assume it’s just ice cracking or perhaps a dog or some other animal,” said author Unto Laine in an interview with Science Alert.
The authors also added that the sounds typically occur only during the most “wild” auroral displays and can sometimes become as powerful as the sound of a waterfall.
This research was recently presented at the UROREGIO/BNAM2022 Acoustics Conference.
