What Are the Northern Lights?
The Northern Lights, also known as aurora borealis, are natural light phenomena observed in regions close to the Earth's magnetic poles. They result from the interaction between the solar wind—a stream of charged particles from the Sun—and the Earth's magnetosphere. When these particles collide with gases in the upper atmosphere, they excite atoms and molecules, producing luminous displays in shades of green, red, violet, and blue that illuminate the night sky. This fascinating spectacle is generally visible in Arctic regions (aurora borealis) and Antarctic regions (aurora australis).
Historical and Contemporary Accounts
Numerous historical and contemporary accounts report sounds associated with the Northern Lights. Descriptions often mention crackling noises, whistling, or rustling sounds. For instance, inhabitants of the Shetland Islands in the early 1930s compared these sounds to a "rustle of silk" or "two boards being slapped together."
Knud Rasmussen and the Discovery of Aurora Sounds
Greenlandic-Danish explorer and ethnologist Knud Rasmussen (1879–1933) was one of the first to document Inuit reports of sounds associated with the aurora borealis. During his Arctic expeditions, he collected testimonies describing how the auroras emitted audible whistling noises. Some Inuit even believed these sounds were the voices of spirits of the dead attempting to communicate with the living. These observations sparked interest among researchers and paved the way for deeper studies into the acoustics of auroras.
The Accounts of Arthur de Capell Brooke and Unto K. Laine
Arthur de Capell Brooke, a 19th-century British explorer, also mentioned sounds associated with the Northern Lights in his travel accounts from Lapland. He described the noises as resembling whispers or faint crackling sounds, particularly noticeable on cold and silent nights.
More recently, Finnish researcher Unto K. Laine conducted acoustic studies on these phenomena and successfully recorded sounds attributed to the Northern Lights. According to his research, published in 2016, these sounds occur approximately 70 meters above the ground and are linked to variations in the Earth's magnetic field caused by auroral activity. His study provided scientific support for centuries of anecdotal reports.
Scientific Approach and Skepticism
Despite these reports, the scientific community has long remained skeptical about the existence of audible sounds produced by the Northern Lights. Auroras typically occur at altitudes exceeding 100 km (62 miles), making it unlikely that sound waves could travel to the ground due to the low air density at such heights. Some researchers have suggested that perceived sounds may be auditory illusions, arising from the awe-inspiring visual display.
Recent Studies and Recordings
Technological advancements have allowed for deeper investigation of this phenomenon. In 2016, a Finnish study led by Unto K. Laine claimed to have recorded audible sounds associated with the Northern Lights, even in the absence of visible auroral activity. These recordings captured crackling, whistling, and popping sounds, suggesting that auroras may indeed produce noises perceptible to the human ear.
Caspar Henderson’s Perspective
In his book "A Natural History of Sound", Caspar Henderson explores the question of auroral sounds. He examines various hypotheses and accounts related to the phenomenon, offering a thought-provoking perspective on how these sounds have been perceived and interpreted throughout history.
Conclusion
The mystery of auroral sounds remains a fascinating topic, blending science, personal testimonies, and folklore. Recent research has provided new insights, but the question is not yet fully resolved. Have you ever had the chance to witness an aurora borealis? If so, did you perceive any distinctive sounds during the experience?
