The Zebra is receiving naturally occurring electromagnetic radio waves emitted from the Earth’s magnetosphere that are audible by the human ear.

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.