What does Earth's magnetic field sound like?
It may seem like an odd question, but scientists have collaborated with artists and musicians to help us hear it. If you want to listen to the spooky-sounding results, you need to head to a square in Denmark's capital, Copenhagen.
Earth's magnetic field is a complex and dynamic bubble that keeps us safe from cosmic radiation and charged particles carried by powerful winds flowing from the Sun.
When these particles collide with atoms and molecules – mainly oxygen and nitrogen – in the upper atmosphere, some of the energy in the collisions is transformed into the green-blue light that is seen as the aurora borealis from high-northern latitudes.
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While the aurora borealis offers a visual display of charged particles from the Sun interacting with Earth's magnetic field, actually being able to hear the magnetic field generated by Earth or its interaction with solar winds is a completely different experience.
European Space Agency's Swarm satellites are being used to understand exactly how our magnetic field is generated. /ESA
Our magnetic field is largely generated by an ocean of superheated, swirling liquid iron that makes up the outer core, starting around 3,000 kilometers beneath our feet and continuing for a depth of around 2,000 kilometers.
Acting like a spinning conductor in a bicycle dynamo, it creates electrical currents, which in turn generate our continuously changing electromagnetic field.
'Bringing art and science together'
Launched in 2013 by the European Space Agency (ESA), three Swarm satellites are being used to understand exactly how our magnetic field is generated. This is being done by measuring precisely the magnetic signals that stem not only from Earth's core, but also from the mantle, crust and oceans, as well as from the ionosphere and magnetosphere.
Swarm is also leading to new insights into weather in space – and an unusual sonic interpretation of the magnetic field.
"The team used data from ESA's Swarm satellites, as well as other sources, and used these magnetic signals to manipulate and control a sonic representation of the core field," explains Klaus Nielsen, musician and project supporter, from the Technical University of Denmark.
"The project has certainly been a rewarding exercise in bringing art and science together."
The resulting audio clip represents the magnetic field generated by Earth's core and its interaction with a solar storm – and it is being played via loudspeakers at Solbjerg Square in Copenhagen, Denmark, at around 8 a.m., 1 p.m. and 7 p.m from October 24 to 30.