What does interstellar space sound like?
Voyager 1 did not record sound with a microphone. Its Plasma Wave Subsystem (PWS) measured electrical oscillations that can be amplified and played as audible tones.
Original NASA recording
Text alternative: two passages contain rising tones. Higher frequency indicates denser plasma; the graph's color shows wave intensity, not the color of space.
What the instrument measured
PWS senses electrical waves in plasma, a gas of charged particles. It does not record ordinary sound traveling through air. Some measured frequencies fall within human hearing, so the signal can be amplified and played through a speaker.
Why the pitch rises
Plasma oscillation frequency is related to electron density. A rising tone corresponds to a denser environment. NASA identifies strong events in late 2012 and spring 2013, excited by disturbances from solar activity.
What scientists learned
The higher density was consistent with interstellar plasma beyond the heliopause. PWS data, together with particle measurements, helped establish that Voyager 1 crossed that boundary in August 2012. This recording is historical data, not a live audio feed.