The aurora borealis is one the most captivating spectacles on Earth. People from around the world make the trek toward the Arctic Circle for a chance at glimpsing the colorful ribbons of light in the night sky. The lights themselves are what most people know, but they're just one part of the phenomenon. The northern lights can be heard as well as seen, and you can listen to them in the clip below.
People have long reported hearing sounds that accompany the lights, but there hasn't been much research to back up the claims until recently. A Finnish study published in 2016 finally confirmed what locals living at the world's highest latitudes already knew: Aurora borealis does produce audio.
The noise has been described as a sizzling or crackling, and scientists still aren't sure where it comes from. The 2016 study suggested that something called a temperature inversion layer is the source. The northern lights occur when the sun shoots solar particles toward Earth. Those particles react with gas molecules in the atmosphere near the poles where the magnetic field is strongest, resulting in a dazzling light show. Conditions have to be just right for the phenomenon to happen, and according to the study, the rare sound requires even more specific criteria.
Temperature inversion layers can form at the end of a warm, clear day. Under these circumstances, warm air from the ground rises and becomes surrounded by layers of cool air above and beneath it. In this position, the warm air layer absorbs positive charges from high in the atmosphere and negative charges from the ground. When the same solar particles that cause the northern lights hit these temperature inversion layers, the charges are released, producing a sound similar to radio static.
The theory is just one possibility, and scientists are still working to identify the noise's cause. In the summer of 2021, an initiative was launched to record the sounds of the lights continuously for 24 hours a day for the first time in history. The citizen scientists involved hope the new data will shed light on the Arctic mystery.
This audio clip from 2011 is a taste of what the researchers are trying to capture. It was recorded by Unto K. Laine—the same acoustician behind the 2016 study—and it captures what could be a pop of the aurora. Take a listen and draw your own conclusions.