Updated: Oct 23, 2019
Space is not empty, nor is it silent. While technically a vacuum, space nonetheless contains energetic charged particles, governed by magnetic and electric fields, and it behaves unlike anything we experience on Earth. In regions laced with magnetic fields, such as the space environment surrounding our planet, particles are continually tossed to and fro by the motion of various electromagnetic waves known as plasma waves. These plasma waves, like the roaring ocean surf, create a rhythmic cacophony that -- with the right tools -- we can hear across space.
Just as waves roll across the ocean or storm fronts move through the atmosphere, disturbances in space, can cause waves. These waves occur as fluctuating electric and magnetic fields plow through clumps of ions and electrons that compose the plasma, pushing some to accelerated speeds. This interaction controls the balance of highly energetic particles injected and lost from in the near-Earth environment.
One type of plasma wave fundamental to shaping our near-Earth environment are whistler-mode waves. These waves create distinct sounds dependent on the plasma they travel through. For example, the region tight around Earth, called the plasmasphere, is relatively dense with cold plasma. Waves traveling inside this region sound much different than those outside. While different whistler-mode waves sing different sounds, they all move in the same way, with the same electromagnetic properties.
Continue Reading at: https://www.nasa.gov/feature/goddard/2017/nasa-listens-in-as-electrons-whistle-while-they-work