The mysterious whisper of the aurora borealis
For centuries strange noises have been said to accompany the exquisite curtains of colour seen in the sky near the Earth's magnetic poles. These sounds are heard often enough to be known as the "whisper of souls of the dead" in Eskimo folklore. However for many years the existence of these sounds has been debated. Some people hear the swish of the aurora while others nearby are left in silence. As a result the auroral noises were often written off as a psychological illusion.
In recent years however scientists believe that they may have discovered what causes the auroral whispers. Aurora are created as the Earth's magnetic field captures charged particles from the solar wind. During these electrical "storms", scientists have recorded abnormally high electric fields and believe that they are responsible for the noises auroras emit. They suggest that they cause "brush discharge", which occurs when electric fields induce an electric potential gradient in objects on the ground. If these objects have points or spikes-such as those on leaves or pine needles, for instance-there can be an electric discharge at their tips that creates an audible crackling.
However a scientist named Keay, believes that the electric fields are rarely strong enough to create brush discharge. He feels that the whispering of the auroras have another cause. He believes that just as with meteor noises auroral sounds are generated by VLF (very low frequency) electromagnetic waves acting on transducers such as hair. These waves seem to be produced by ions and electrons from the solar wind that are reflected back and forth in the Earth's magnetic field.