video transcript

The audio was recorded by researchers at the University of Iowa, who were monitoring data being transmitted by an instrument suite aboard the Radiation Belt Storm Probes. The two probes were launched in early September to collect information about the sun's influence on Earth by studying particles in the Van Allen radiation belts that enciircle the Earth. One of the many instruments aboard is called the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS). EMFISIS measures electric and magnetic field components in the belts but, on September 5, it also captured what the scientists call "several notable peak radio wave events in the magnetosphere that surrounds the Earth." They say the radio waves, which are at frequencies that are audible to the human ear, are emitted by the energetic particles in the Earth's magnetosphere. The "chorus" is a sound well-known to space scientists. It is more easily detectable in the morning which "along with the chirping sound is why it's sometimes referred to as 'dawn chorus'."