NASA’s listening to the void
The Perseus galaxy cluster is an 11 million-light-year-wide grouping of galaxies enveloped in hot gas. Those clouds of hot gas are the key to the sound waves you can hear in the clip shared by NASA (embedded below). Decades ago, scientists discovered that pressure waves emanate from Perseus’ interior. These waves ripple through the hot gas surrounding the galaxy cluster, and these waves can be translated into sound.
Sounds on Earth occur when sound waves vibrate atoms and molecules in the air. In space, things are somewhat different. Space is a vacuum, meaning vibrations don’t have any air to vibrate and make noise in. Crucially though, that doesn’t mean the vibrations aren’t there. That’s the principle the NASA scientists put into effect for their sound clip.
The misconception that there is no sound in space originates because most space is a ~vacuum, providing no way for sound waves to travel. A galaxy cluster has so much gas that we’ve picked up actual sound. Here it’s amplified, and mixed with other data, to hear a black hole! https://t.co/RobcZs7F9e
— NASA Exoplanets (@NASAExoplanets) ) August 21, 2022
In the case of Perseus’ black hole, the cosmic giant is so close to the cluster’s gas clouds that it can create sound wave vibrations in the form of gas ripples. In 2003, a team of astronomers from NASA’s Chandra X-ray Observatory took astronomical data of these ripples and translated them into sounds. Unfortunately, those sounds were a massive 57 octaves below middle C, meaning they couldn’t be heard by human ears.
Remixed black hole sounds
To make the sounds in the new clip audible to the human ear, NASA scaled the sound data up by 57 and 58 octaves so we can all listen to the massive black hole at the center of the Perseus galaxy cluster. In a blog post, NASA wrote that the sound waves “are being heard 144 quadrillion and 288 quadrillion times higher than their original frequency.”