The Northern Lights are recognized as one of the most unique natural wonders in the world. Every year, tourists flock to the Arctic for a chance to witness the night sky light up in a menagerie of brilliant colors. Auroras have been observed by humans for thousands of years, with many myths and theories springing up in their wake, but there’s one question that is rarely answered by these speculations: do the Northern Lights make a sound?
The answer is yes. While some observers in the past have reported bizarre noises emitting from auroras, it wasn’t until recently that the mechanics behind them were studied by scientists. Read on to learn why the Northern Lights make sound and what it sounds like.
Do the Northern Lights Make a Sound?
While the visual beauty of the Northern Lights has been noted by observers for generations, it wasn’t until relatively recently that they began reporting unusual noises alongside auroras. Aurora noises have been described as “eerie,” akin to radio or TV static, and for years were dismissed as either caused by weather events or otherwise unrelated to the auroras themselves. However, recent scientific studies have confirmed that auroras do indeed make a sound, though in many cases this sound is not audible to humans.
To understand why the Northern Lights make a sound, it’s important to know how the Northern Lights work in the first place. Auroras are created when solar wind, a term used for the charged particles that the sun regularly gives off, comes into contact with the magnetosphere, the protective barrier generated by Earth’s magnetic field. The magnetosphere is responsible for deflecting harmful interstellar radiation and is part of the reason why Earth can support life.
When solar wind impacts the Earth at the points where the magnetosphere intersects with the atmosphere (the North and South Poles), charged particles within the solar wind excite the atoms in the atmosphere. Atoms are composed of three types of particles: protons, which carry a positive charge; neutrons, which carry no charge; and electrons, which carry a negative charge. Protons and neutrons are located in the nucleus, the center of the atom, and electrons orbit the nucleus, similar to how the moon orbits the Earth or the Earth orbits the sun.
When atoms become excited, electrons migrate from their existing orbits to higher-energy orbits that are further away from the nucleus. When those electrons return to their original orbits, they give off a photon, a unit of light. Countless atoms being excited results in a massive amount of light being given off, creating the Northern Lights. The effect is similar to a neon sign, which uses electricity to excite neon gas atoms, creating light.
Originally, scientists believed that auroras were incapable of creating sound. One popular thesis suggested that the noises people heard during auroras were being generated by trees. During an aurora, the surrounding atmosphere can hold an unusually high amount of electricity, creating a difference in charge between objects on the ground and the surrounding air.
Pointy objects, such as pine cones and leaves, are capable of discharging electricity in the same fashion that metal doorknobs can sometimes discharge static electricity into your hands when you touch them. It was believed that auroras caused leaves and pine cones to discharge large amounts of electricity into the air, creating the crackling noise that observers sometimes heard.
However, in 2012, a Finnish scientific study confirmed that aurora noise originates from 230 feet (70 meters) in the air, far higher than any treetop in the Arctic Circle. The study explained that aurora noise is generated by an inversion layer, a portion of the atmosphere where temperatures rise with altitude instead of decreasing as they normally do. Inversion layers are common after calm, sunny days and are created after sunset, when warm air rises as the Earth’s surface cools and calm weather conditions prevent the warm air from mixing with colder air.
According to the study, inversion layers act as a kind of lid for electricity, trapping negative electrical charges in the air below them and positive charges in the air above. While this normally doesn’t create any kind of audible effect, during an aurora, the charged particles from the sun cause the inversion layer to be broken, mixing positive and negative charges and creating the static, crackling noise that aurora viewers sometimes notice.
The report noted that inversion layers typically form in the atmosphere at 230 feet (70 meters) above the ground, which is also where the report noted that aurora sounds originate from. This confirmed their assertion that inversion layers are the cause of aurora noise.
As a general rule, aurora sound is difficult to hear due to the fact that inversion layers require very specific conditions to form and auroras need to be of a certain size and strength in order to penetrate the inversion layer in the first place. Aurora noise is more common when the sun is at the peak of its 11-year cycle due to the fact that solar wind is more common and larger in size. As a result, there is no guarantee that you will be able to hear aurora noise when you go out looking for auroras.
Long dismissed as a figment of observers’ imaginations, modern science has confirmed that aurora noise is very real. The chance of hearing an aurora is low, requiring both uniquely calm weather and particularly strong solar storms. However, if you journey to the north to watch the Northern Lights, there is every chance you may get to hear the aurora instead of merely just seeing it. If you’re curious about auroras, why not book a Northern Lights trip and see for yourself?