If you have ever wondered if the Northern lights create a sound, you may not be alone.
According to Aalto University in Finland, folktales claiming the aurora borealis makes sound are correct.
Researchers working simultaneously with the Finnish Meteorological Institute (FMI) captured a recent unamplified recording of the auditory phenomenon, the first such evidence that the aurora borealis may produce a strange sound.
According to the Geophysical Institute of the University of Alaska-Fairbanks, the aurora borealis is a luminous glow of the upper atmosphere which is caused by energetic particles that enter the atmosphere from above. The energetic particles that make the aurora borealis come from the magnetosphere and may create a sound as individuals witness the atmospheric phenomena.
While FMI was taking measurements of geomagnetic disturbances, researchers used three microphones to capture up to 8 hours of recordings. Analyzing these recordings in relation to the FMI measurements, researchers were able to determine that the sounds formed about 70 meters above the ground level in the measured case.
“Our research proved that, during the occurrence of the northern lights, people can hear natural auroral sounds related to what they see,” said Aalto University Professor Unto K. Laine. “In the past, researchers thought that the aurora borealis was too far away for people to hear the sounds it made. This is true. However, our research proves that the source of the sounds that are associated with the aurora borealis we see is likely caused by the same energetic particles from the sun that create the northern lights far away in the sky. These particles or the geomagnetic disturbance produced by them seem to create sound much closer to the ground.”
Although the recording and measurements correlate with this theory, further research into the details of these auditory occurrences—why they sometimes occur under these conditions, and also why they often do not—is necessary to truly understand the way it occurs and the relationship between the aural and visual phenomena.
The article covering the development on the Aalto University website says, “Other people who have heard the auroral sounds have described them as distant noise and sputter.” The distinct, unamplified clap heard in the recording certainly seems noticeable enough.
However, the article says that these mixed reviews and recordings only inspire further research. The article states, “because of these different descriptions, researchers suspect that there are several mechanisms behind the formation of these auroral sounds.” Researchers note that the study will likely produce enough interest to bring in funding for an additional study, however, it remains unclear when additional research will take place.
A diagram accompanying the recording suggests that interference and reflections of particles or sound from the Earth contribute to the appropriate auditory conditions, although scientists cannot be sure.
In contrast to the very clear clap of the recording, the Aalto University article says, “These sounds are so soft that one has to listen very carefully to hear them from the ambient noise.” This implies a wide variety in the auditory experiences researchers and storytellers describe, and perhaps will need a variety of experimental work to entirely explain.
It remains unclear how the findings will be put to use in studying the Northern lights. Scientists studying the Earth’s magnetic field remain mystified by many elements of the protective force field. The study may allow scientists to further exam how the Earth’s atmosphere interacts with the massive amount of charged particles that bombard Earth each second.
At least in terms of this instance, a detailed account is possible. The Aalto University study will be published “in the proceedings of the 19th International Congress on Sound and Vibration,” held in Vilnius, Lithuania between the 8th and 12th of July 2012.