The famous Northern Lights. Image: Oxana Gracheva/Shutterstock
There’s a cacophony of sound thousands of kilometres above our heads, and NASA is allowing us to listen in.
Space is always thought of as a cold, silent vacuum, but behind the visible universe lies an orchestra of sound at an atomic level.
For example, regions that have magnetic fields – such as the one that surrounds our planet – contain energetic, charged particles thrown around by the motion of various electromagnetic waves, known as plasma waves.
These act much like the waves we see down in the ocean, creating rhythmic ripples of particles.
The different types of plasma trigger different sounds. Image: NASA’s Goddard Space Flight Center/Mary Pat Hrybyk-Keith
Now, NASA has managed to record these waves of electrons to reveal a soundtrack unlike anything you’re likely to hear on Earth, with varying sounds depending on the plasma that is traversed.
In the example below, we can hear ‘chorus’ radio waves from within Earth’s atmosphere – captured by instruments aboard NASA’s Van Allen Probes – which are created when electrons are pushed towards the night side of our planet.
We can also hear a ‘hiss’ reminiscent of the white noise of a radio station, possibly caused by lightning strikes or chorus waves that have leaked inside the region closest to Earth, called the plasmasphere.
Both cold and dense, the plasmasphere changes the sounds we hear, differing from the outermost region of Earth’s magnetic field.
Out where the plasmasphere is warmer and more sparse, whistler waves are created, which better resemble the sound of a flock of birds.
Helps protect satellites
“NASA scientists, with the help of the Van Allen Probes mission, are working to understand the dynamics of plasma waves to improve predictions of space weather, which can have damaging effects on satellites and telecommunications signals,” the space agency said.
“As a part of their observations, the scientists have recorded these eerie sounds made by different plasma waves in the particle symphony surrounding Earth.”
In doing so, NASA hopes to better understand how electrons are accelerated and lost from the radiation belts, and help protect satellites and telecommunications in space.
