subject: Sounds Of The Northern Lights [print this page] Our Earth is continually being bombarded with particles from the Sun. During periods of high sunspot activity or solar flares, more particles enter the Earths magnetic field and collide with atoms in our upper atmosphere. The output of these collisions is a release of energy, which is in the form of heat, light and sound. The light is what can be seen at the poles after nightfall i.e. the Aurora Australis and the Aurora Borealis. It appears as sweeping curtains in shades of green, yellow and pink, and has fascinated onlookers for centuries. But the sounds of the Northern Lights are only just beginning to be understood.
It is thought that the noises made by the Aurora Borealis were first noticed in England in 1882 when telegraph operators picked up strange whistling sounds in their headphones. But it wasnt until the 1930s that the connection with the Northern Lights was made. It is believed that the solar particles generate very low frequency electromagnetic waves, creating a type of natural radio, which can be picked up around the world with specially designed receivers.
An array of different sounds from the Northern Lights has been recorded, both by scientists and amateur enthusiasts. Some are described as whistles, whilst others hiss, squeak, hum, growl, click and clap. In any case, the noises that are picked up are intriguing, exciting and ethereal.
Now Finnish researchers believe that they have found proof that the noises made during an auroral event can be picked up by the human ear. Researchers from the Aalto University set up microphones at several places above the ground in order to calculate the source of the sounds made by the Northern Lights. They believe that noises are generated approximately 70 metres above ground level.
It has previously been thought that the noises were too high pitched to be picked up by the human ear. However, the Finnish scientists seem to have disproved this theory and believe that humans can hear the sounds of the Northern Lights despite the distance between the Aurora and ground level.
The evidence that has been collected to date is not quite accurate or detailed enough to be able to say with confidence that the sounds of the Northern Lights are audible to people on the ground. They are so quiet that it could be difficult to pick them out from background noise.
