Earth’s atmosphere produces a natural sound and beams it off into the universe, Space.com reports. The sound—a painful series of chirps and whistles—is made by the collision of charged particles from the solar wind with Earth’s magnetic field.
Scientists had long theorized that the resulting radiation simply dissipated into space, but new research shows the radiation is beamed out along a narrow plane. As such, researchers believe, it could be more easily intercepted by anyone, or anything, listening in. (More space stories.)