Carl Sagan, for all his poetry and beautiful writing about Earth and our life on it within the universe, never suggested the Milky Way was a musical galaxy.
Turns out, he missed an opportunity to (ahem) sing the praises of the jazzy nature of our cosmic home.
Mark Heyer, an astronomy professor at the University of Massachusetts Amherst, and Greg Salvesen, a post-doctoral student at the University of California Santa Barbara, worked across the country to discern the score of the night sky.
Heyer developed an algorithm to translate the movement of the gases in the galaxy and turn them into musical notes. “This musical expression lets you ‘hear’ the motions of our Milky Way galaxy,” he says. “The notes primarily reflect the velocities of the gas rotating around the center of our galaxy.”
Salvesen recently launched the Astronomy Sound of the Month website, which “explores how sound complements more traditional astronomy data analysis. Besides, making sounds out of real astronomy data is just plain cool!”
The two worked together to write “Milky Way Blues,” a composition that lets people hear the movement and activity within the galaxy we call home.
“’Milky Way Blues’ has a bit of a player piano look and feel to it, which is what we wanted,” Salvesen said. “What you’re hearing is the rotation or the motion of gas in our galaxy.”
The space between stars in the sky is filled not with nothing, despite how it looks, but with gas in one of three phases: atomic, molecular and ionized. Each phase was assigned differing tones and lengths of notes, Heyer was able to express the movement we wouldn’t normally see or be able to grasp.
“Astronomers make amazing pictures, but they’re a snapshot in time and therefore static. In fact, stars and interstellar gas are constantly moving through the galaxy but this motion is not conveyed in those images. The Milky Way galaxy and the universe are very dynamic, and putting that motion to music is one way to express that action.”
He and Salvesen went with a pentatonic scale, with five notes instead of seven, and a minor key because, as Heyer said, “when I heard the bass notes it sounded jazzy and blue.”
The notes and tones were not manipulated in order to make them more pleasing to the ear, he stresses. “By turning what we actually observe with a radio telescope into a musical scale it gives us familiar tones that sound surprisingly like music with which we’re familiar.”
Gases coming toward the Earth are coloured blue on Salvesen’s rendering and have higher-pitched tones on Heyer’s composition. Gases moving away from Earth are lower on the scale and are coloured red. There’s a full complement of instrumentation used as well: acoustic bass representing atomic gases, wood blocks and piano standing in for molecular gases and saxophone used to give sound to ionized gas.
The two worked together for several months on the composition, which was released on the eve of one of the high holy days of the nerd calendar: May 4.
Now that you’re thinking and listening skyward, check this out too: the European Space Agency has released what’s being hailed as the most accurate census of the stars in the Milky Way, detailing the motion, distance, brightness and colour of the 1.7 billion stars in our celestial neighbourhood.