Imagine the rings of Saturn as strings of a harp that you can strum to create music. Or the seven terrestrial planets that orbit the red dwarf star TRAPPIST-1 as piano notes and beats of a drum. Space and sound don’t necessarily go hand in hand but it is a combination that is increasingly finding a voice.
For instance, the US space agency Nasa, keen that you hear the sounds of the Mars-bound Perseverance rover, disclosed in November that a microphone aboard it had recorded the sounds of the spacecraft as it moves towards the red planet.
Three years ago, a trio of astrophysicists and musicians started a science-art outreach project, SYSTEM Sounds, which converts majestic space images into music and sound. The idea came to Matt Russo, an astrophysicist, musician and sonification specialist, who was then struggling to balance his postdoctoral astrophysics research and music career. “At just the right time, astronomers discovered the most musical solar system, TRAPPIST-1. I teamed up with my bandmate Andrew Santaguida and fellow astrophysicist Dan Tamayo to convert the rhythms and harmony of this system into music,” says Russo, on email. With its interactive apps and music videos, SYSTEM Sounds has been trying to make astronomy more accessible.
Using data sonification, it has converted everything—from images of the universe captured by the Hubble Space Telescope to the impact craters on the Moon. In 2018, Russo, Santaguida and Tamayo even collaborated on exhibits like the sound-based planetarium show, Our Musical Universe, at the Dunlap Institute for Astronomy & Astrophysics, Toronto, and One Sky, an exhibit that was displayed at the Nuit Blanche Toronto art event. Their latest work is a website, My Starry Night, that lets you see and hear stars gliding overhead on any given night.
Apart from their own website and social media handles, listeners can tune in to these cosmic sounds on platforms like YouTube and Spotify. Their work even featured in Calm, the popular meditation and sleep app.
“It’s extremely exciting to make astronomical data audible for the first time. It’s equal parts discovery and creativity,” says Russo. A close look at the project website explains that images captured by the Hubble telescope, for instance, were converted into sounds based on two principles: light and colour.
SYSTEM Sounds scanned the images of galaxy clusters from left to right while generating sound waves based on the brightness and position of the light received by the space telescope. “Brighter light is heard as louder sound and the tone’s frequency increases from the bottom up to the top of the image. Objects near the top of the image then produce the higher-pitched tones,” the website explains.
Similarly, for images of planetary nebulae like the Helix Nebula, Russo and the team mapped the bright, vibrant colours and converted them into sounds. Red light is mapped to lower pitches, blue to higher ones. “This is a natural mapping since the frequencies of light increase from red to blue in the same way that frequencies of sound increase from low to high pitches,” the website explains. The end product is a mystifying sound, almost like a shrill scream that rises and then fades.
The same code was used to convert Hubble’s 30th anniversary image of the Cosmic Reef, two nebulas that are part of a vast star-forming region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. The sonification of the famous “Pillars of Creation” image is an excellent example of SYSTEM Sounds’ work. The sounds of these elephant trunks made of interstellar gases are borderline sci-fi, a distortion of time and space.
Russo says that in many cases, whether it’s solar systems or oscillating stars, the musicality already exists in nature. “We simply need to make it audible for human ears,” he adds. “Converting two-dimensional images into sound is usually difficult since we need to make more choices to create an intuitive mapping from visual to audio information. Multi-wavelength images add even more dimensions and it’s often difficult to communicate information captured by multiple telescopes in a single audio stream,” he explains.
The team is currently working on new sonification projects with Nasa and the Chandra X-Ray Center in Cambridge, US, that will enable us to hear some of the largest structures in the universe.
Apart from the ingenuity and creativity at play—using the Cassini spacecraft as a pick to strum the rings of Saturn is just brilliant—the beauty of this project lies in its ability to bridge the distance between listeners and cosmic entities.
The Helix Nebula, for instance, might be one of the cosmic objects closest to Earth but it is still approximately 695 light years away. The music that SYSTEM Sounds creates brings it, and other wonders, that much closer.