An international team of scientists using data from ESA's cluster missions has created the first recording of the eerie "song" that the earth makes when hit by a solar storm.
The song comes from waves generated in the Earth's magnetic field through the collision of the storm. The storm itself is the eruption of electrically charged particles from the sun's atmosphere. The sun constantly emits streams of charged particles, but the Earth's magnetic field prevents these particles from entering our atmosphere. However, explosions on the sun's surface can send a huge cloud of particles and radiation into space. If these solar storms are directed at the earth, when they hit, they can disrupt our satellite systems, cause widespread blackout and affect GPS systems.
To create the recording, the team analyzed two decades of data from ESA's Cluster mission, four spacecraft that have orbited Earth in formation since 2001 and examined our planet's magnetic environment and its interaction with the solar wind.
As part of their trajectories, the Cluster spaceship flies repeatedly through what is called foreshock, the first region that particles encounter when a solar storm hits our planet. The team found that in the early part of the mission, from 2001 to 2005, the spaceship escaped through six such collisions and recorded the waves generated.
The new analysis shows that during the collision, magnetic waves are released that are much more complex than initially thought.
When the frequencies of these magnetic waves are transformed into audible signals, they give rise to a psychedelic song that is more reminiscent of sound effects from a science fiction film than from a natural phenomenon.
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In quiet times, when no solar storm hits the ground, the song is lower in pitch and less complex. However, when a solar storm hits, the frequency of the wave roughly doubles, depending on the strength of the magnetic field in the storm.
University of Helsinki astrophysicist Lucile Turc is lead author of the study, published November 18, 2019 in the peer-reviewed journal Geophysical research letters. She said in a statement:
It's like the storm changes the attitude of the pre-shock.
The researchers said that not only does the frequency of the wave change, but that it also becomes much more complicated than the individual frequency for quiet time. When the storm hits the front, the wave breaks into a complex network of different higher frequencies. According to a statement about the research:
The changes in the pre-shock have the power to influence how the solar storm spreads down to the earth's surface. While it is still an open question exactly how this process works, it is obvious that the energy generated by the waves in the pre-shock cannot escape back into space, as the waves are pushed to the earth by the incoming solar storm.
Before they reach our atmosphere, however, the waves encounter another barrier, called Bock Shock, which is the magnetic region of space that brakes solar wind particles before colliding with the Earth's magnetic field. The collision between the magnetic waves changes the behavior of the arc shock, and may possibly change how it processes the energy from the incoming solar storm.
Behind the arc shock, the Earth's magnetic field begins to resonate at the frequency of the waves and this contributes to the transmission of the magnetic disturbance all the way to the ground. It is a fast process that takes about 10 minutes from the wave generated at the front end until its energy reaches the ground.
Bottom line: Listen to a creepy song on earth hit by a magnetic storm.
Source: First observations of the disturbance of the earth's prewave wave field under magnetic clouds