Eerie 'Song' of Earth's Magnetic Field During a Solar Storm Captured by Scientists

The eerie "song" created when a solar storm hits Earth's magnetic field has been recorded by scientists. By analyzing data from the European Space Agency's Cluster spacecraft, researchers discovered how solar storms "profoundly modify" the region of space just beyond the magnetic field—a finding that could help find ways to mitigate their potentially devastating impact.

The sun is constantly sending out a stream of charged particles known as the solar wind. Earth is protected from this by its magnetic field, preventing these particles from entering our atmosphere. However, explosions on the sun's surface can send a huge clouds of particles and radiation out into space. If these are directed towards Earth, when they hit they can cause major disruptions to our satellite systems, cause widespread blackouts and affect GPS systems.

It is estimated that if a big solar storm hit Earth today, the economic impact could reach trillions of dollars. Understanding exactly what happens when a solar storm hits could help the development of mitigation strategies.

In a study published in the journal Geophysical Research Letters, a team of scientists led by Lucile Turc, from the University of Helsinki, Finland, used data from Cluster—four identical spacecraft that have been orbiting Earth since 2001 and have flown through the foreshock repeatedly. They found that between 2001 and 2005, Cluster flew through six solar storms and recorded the waves generated.

foreshock solar storm
Artist impression of a solar storm hitting the foreshock. Earth is the dot to the left surrounded by the protective bubble of the magnetic field. Vlasiator team, University of Helsinki

The foreshock is the first region that the particles from the sun reach on their way to Earth. During a collision with a solar storm, the foreshock was found to release magnetic waves. These waves were then transformed into frequencies that could be heard as audible signals—allowing them to hear the "song."

"Our study reveals that solar storms profoundly modify the foreshock region," Turc said in a statement. "It's like the storm is changing the tuning of the foreshock."

Under normal circumstances, the "song" is lower in pitch. However, when a solar storm hits, the frequency doubles and wave activity becomes much more complex. Further simulations confirmed their findings.

Researchers say the changes that take place in the foreshock could affect how the solar storm reaches Earth. Instead, the waves produced cannot escape into space and are pushed down towards Earth. When they reach the magnetic field, the waves transmit the magnetic disturbance to the surface of the planet.

The team now hopes to work out how the waves are generated. "We always expected a change in frequency but not the level of complexity in the wave," Turc said.