In the emptiness of space, Voyager I detects plasma 'hum'

NASA's Voyager I spacecraft has long since zipped past the edge of the solar system through the heliopause - the solar system's border with interstellar space - into the interstellar medium. Now, its instruments have detected the constant drone of interstellar gas (plasma waves).

source https://www.sciencedaily.com/releases/2021/05/210510113603.htm