Listen up.
Listen up. Ian Norman/CC by SA 2.0

Mark Heyer, an astronomer at the University of Massachusetts Amherst, has spent more than a quarter of a century dreaming about the sounds of space.

At first, he just wanted to get a better grasp on his data. Heyer studies galactic gases, and in the 1990s, he was using a telescope to collect 3-D measurements of specific clouds of gas in the Milky Way. He could see that the clouds were turbulent, often collapsing or expanding, but when he examined the data with the help of a computer, the velocity variable got lost. Heyer needed a way to visualize not just two points on a map, but what happened between them. Translating three dimensions into something viewable on a two-dimensional screen required a little creativity, and he landed on the idea of transforming the motion into sound. As you moved your cursor around, you’d hear something different; various pitches corresponded to various velocities. “Initially, it was a functional idea,” he says. “But if you’re going to that effort, why not make music?”

Eventually he wanted to scale up to a musical composition that captured the “sound” of the atomic, molecular, and ionized gases across the Milky Way. “I thought it would just sound like noise or randomness,” he says. “But the more I thought about it, I realized you’d be hearing the rotation of the galaxy,” which has “big, obvious motions,” he says. Heyer suspected that, by transforming the data collected by radio telescopes into a musical scale, he would end up with something rather consonant.

He just wasn’t sure exactly how to pull it off. Heyer couldn’t compose and play the music himself—he has dabbled with guitar and mandolin and once built a dulcimer, which he “can hack on a little bit,” but he’s not an especially skilled musician. (“I know just enough to be dangerous,” he says.) Recently, he discovered that he could outsource some of the work to an algorithm, and that sounded promising.

Once he had the tools, Heyer knew he wanted to first try emulating the instruments of a jazz ensemble—but which ones? His simulator has over 100 instruments. Some didn’t make the cut because they wouldn’t be able to leap between octaves they way they’d need to in order to bring the data to life. The glockenspiel was an early casualty, as was the flute. “It’s such a high-pitched instrument, and there are so many low notes,” Heyer says. “You’d never hear it.”

In the final composition, titled Milky Way Blues, baritone saxophone stands in for the ionized gas, the bass represents atomic gas, and piano and wooden blocks draw from the data about molecular gas. (To account for the span of the Milky Way, Heyer collated data from different sources and hemispheres.) High notes denote gas moving toward Earth, and low notes reference gas moving away. The longer the note, the greater the intensity. Heyer tried to keep tinkering to a minimum in order to preserve the integrity of the data the whole thing is based on. You can listen on Astronomy Sound of the Month, or above.

The ditty is a bit goofy, but it’s a creative way to help bridge the gap between what we know and what we can imagine. It’s a twist on Heyer’s original impulse to visualize data, but tailored for people who aren’t necessarily scientists. Pictures don’t give us the complete story of our galaxy, and it’s hard to fill in the gaps. Though Earth-locked viewers are accustomed to seeing still images of our galaxy, all twinkling and sherbet-hued, it’s actually kinetic and in constant motion. We can know that, intellectually, but it’s hard to translate it into something relatable. Heyer says that’s a common refrain. “Even astronomers don’t really understand the vastness of space,” he says. “It’s mind-boggling.” He can calculate the distance from Earth to a particular star or cloud, for instance, “but perceptually, I don’t know what that means.” Taking a cue from the corner jazz band, tooting and blaring away, is one strategy for making the whole thing just a tiny bit easier to wrap our minds around.

Heyer says his composition is landing on receptive ears; two people have already reached out to see if they can snag a copy of the score to play themselves. In the future, Heyer might zero in on different parts of the galaxy, too—after all, if you translate motion into music, the supermassive black hole at the center of our galaxy would sound much different than places farther away, where gases are more sparse. Sampling different regions of our solar neighborhood would be like a sonic road trip to a place we wouldn’t otherwise hear—and maybe never dreamed we could.