Humans can’t hear sounds in space, but there are sounds waves moving through the rarefied plasma that fills interplanetary and even interstellar space, the gaps between the stars. Now, thanks to Voyager 1, we can say what interstellar gas sounds like: a constant hum. Voyager 1 is the furthest human-made object from Earth. Since 2012 when it crossed the heliopause and left the Solar System, it has been traveling in interstellar space, giving humanity our first direct observations of what the space between stars is really like. Previous studies of this interstellar plasma focused on shockwaves, some of which were triggered by the Sun. This new study, published in Nature Astronomy, looks at the constant background noise of the plasma waves.