Researchers discover cosmic chirps far from Earth

Researchers have recorded “chorus” waves far from Earth for the first time – where they were least expected. This discovery raises many questions.

Scientists have detected cosmic sound waves at a distance from Earth that has never been greater. These waves, called choruses, were captured by four satellites launched in 2015 and responsible for studying the magnetic fields of the Earth and the Sun, we can read in an article published Wednesday in the journal “Nature”. Chorus waves had already been recorded before, but never more than 100,000 kilometers away as is currently the case.

Chorus waves are likely generated by the interaction between solar winds and the planets’ magnetic fields. When converted to audio signals, they sound like high-pitched birdsong. Radio antennas already picked them up decades ago, notably at a research station in Antarctica in the 1960s. And two American space probes heard the song of the Earth’s radiation belt at a distance less than that of the discovery which has just been published.

The newly discovered chorus waves were found in a region where Earth’s magnetic field is stretched, something scientists had not predicted. “It raises a lot of new questions about the physics that might be possible in this region,” said space physicist Allison Jaynes of the University of Iowa, who was not involved in this work. “It’s very captivating, very compelling,” Jaynes said. “We definitely need to find more processes like this.”

Chorus waves have also been discovered near other planets, including Jupiter and Saturn. They can generate high-energy electrons capable of disrupting satellite communications. “They are one of the most powerful and important waves in space,” study author Chengming Liu of Beihang University wrote in an email.