Despite being essential to life on Earth, the magnetic field is not something we can actually see by itself or ever hear. But, remarkably, scientists at the Technical University of Denmark have taken magnetic signals measured by ESA’s Swarm satellite mission and turned them into sound – and for something that protects us, the result is pretty terrifying.
The Earth’s magnetic field is a complex and dynamic bubble that shields us from cosmic radiation and charged particles carried by strong 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 converted into the green-blue light characteristic of the northern lights, which can sometimes be seen from high northern latitudes.
While the aurora borealis offers a visual representation of charged particles from the Sun interacting with the Earth’s magnetic field, being able to hear the magnetic field generated by the Earth or its interaction with the solar winds is another matter.
Our magnetic field is largely generated by an ocean of superheated, swirling liquid iron that forms the outer core some 3000 km below our feet. Acting like a rotating conductor in a bicycle dynamo, it creates electric currents, which in turn create our ever-changing electromagnetic field.
Launched in 2013, ESA’s three Swarm satellites are used to understand exactly how our magnetic field is created by precisely measuring the magnetic signals coming not only from the Earth’s core, but also from the mantle, crust and oceans, as well as from ionosphere and magnetosphere. The Swarm also leads to new ideas about space weather.
Musician and project promoter Klaus Nielsen, from the Technical University of Denmark, explains: “The team used data from ESA’s Swarm satellites, as well as other sources, and used these magnetic signals to manipulate and control an audio representation of the nuclear field. The project was certainly a rewarding exercise in bringing art and science together.”
It may sound like nightmares, but, remarkably, this audio clip represents the magnetic field generated by the Earth’s core and a solar storm.
“We gained access to a very interesting sound system consisting of over 30 loudspeakers dug into the ground in Solbjerg Square in Copenhagen.
“We’ve set it up so that each speaker represents a different location on Earth and shows how our magnetic field has fluctuated over the past 100,000 years.
“Throughout this week, visitors will be able to hear the amazing hum of our magnetic field – so if you’re in Copenhagen, come and see this unique opportunity.
“The hum of the Earth’s magnetic field is accompanied by a representation of a geomagnetic storm resulting from a solar flare on November 3, 2011, and it sounds pretty scary indeed.”
The intention, of course, isn’t to scare people – it’s a quirky way of reminding us that the magnetic field exists, and although its hum is a bit unsettling, the existence of life on Earth depends on it.
Loudspeakers in Solbjerg Square in Copenhagen, Denmark will broadcast the hum of the Earth’s magnetic field on October 24–30 around 08:00, 13:00 and 19:00.
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