An international team of astronomers has discovered mysterious “singing waves” in an unexpected region of space, raising new questions about their origin.

“Singing waves,” also called chorus waves, or chirp waves, are second-long bursts of electromagnetic radiation that occur high above the Earth’s surface. Converted to audio format, they are reminiscent of a bird chirping. These phenomena have been studied for decades and are thought to be caused by the instability of plasma, an ionized gas that emits electromagnetic waves in distinct patterns.
Previously, similar waves were found at a distance of up to 50,000 kilometers from the Earth, where the magnetic field of our planet resembles a classical dipole with clear poles. Physicists believed that this feature created the plasma instability necessary for wave formation.
However, new research published in Nature has detected these waves at a much greater distance — about 165,000 kilometers from Earth. In this zone, the magnetic field is highly distorted, indicating that the coupling of “singing waves” to the dipole magnetic field is not as important as previously thought.
“The similarity of these waves to those occurring closer to Earth indicates that their formation can occur anywhere in space, regardless of the local environment,” the researchers said in their paper.
The study was based on data from NASA’s MMS (Magnetospheric Multiscale Mission) satellite launched in 2015. This vehicle provided detailed images and captured waves at a considerable distance from Earth.
An important part of the study was the confirmation of one of the previously theorized mechanisms — energy transfer from plasma particles to chorus waves. This process was first observed in regions of low electron density known as electron holes. This confirms the phenomenon of electron cyclotron resonance, where the frequency of electrons coincides with the frequency of waves, enhancing energy transfer.
“Electron holes associated with chorus waves have long been studied through simulations, but now we have been able to observe them directly,” the study authors write.
“Singing waves” have also been found on other planets such as Mars, Jupiter and Saturn. They are among the most powerful sources of electromagnetic radiation in space and affect the Earth’s radiation belt, and can also pose a threat to satellites. Studying these waves helps to better predict their activity and avoid potential risks.
Earlier we covered what we would hear on other planets.
According to sciencealert.com