Set to music, telescope observations from the center of the Milky Way create a calm, bright melody with notes of xylophone and piano. Meanwhile, the iconic Pillars of Creation in the Eagle Nebula look like a mysterious science fiction score. And the rest of the Cassiopeia A supernova is a radical symphony.
These musical performances, or sonications, were released on September 22 by NASA's Chandra X-ray Center. “Listening to the data gives (people) another dimension to experiencing the universe,” says Matt Russo, an astrophysicist and musician at the SYSTEM Sounds astronomy outreach project in Toronto.
Sonification can make cosmic wonders more accessible to people with blindness or visual impairment and complement images for the sighted. SYSTEM Sounds teamed up with Kimberly Arcand, a visualization scientist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, to create the new pieces.
Christine Malec, music and blind astronomy enthusiast, vividly remembers the first sonication she ever heard: a depiction of the TRAPPIST-1 planetary system that Russo performed during a planetarium show in Toronto (SN: 22/02/17). “I had goosebumps because I felt I had a slight impression of what it’s like to perceive the night sky or a cosmological phenomenon,” he says. Music offers data "a spatial quality that astronomical phenomena have, but that words cannot convey."
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The new versions combine data from multiple telescopes tuned into different types of light. Sonication of an image of the center of the Milky Way, for example, includes observations from the Chandra X-ray Observatory, optical images from the Hubble Space Telescope, and infrared observations from the Spitzer Space Telescope. Users can listen to the data from each telescope alone or from the trio in harmony.
New “sonifications” of data translate telescope images into songs. Listen to observations of celestial objects around the Milky Way, from the galactic center to the Pillars of Star Creation in the Eagle Nebula.
As a cursor traverses the image of the galactic center from left to right, showing an extension of 400 light-years, Chandra’s X-ray observations, reproduced on the xylophone, trace superhero gas filaments. Hubble’s observations on the violin highlight star-forming pockets, and Spitzer’s piano notes illuminate infrared clouds of gas and dust. Light sources near the top of the image play in higher tones and brighter objects play louder. The song crescendos around a luminous region in the lower right corner of the image, where gas and bright dust envelop the galaxy’s supermassive black hole.
Caping the instruments on top of each other gives the observations an element of texture, says Malec. "It appealed to my musical sense, because it was done in a harmonic way, it wasn't discordant."
That was on purpose. “We wanted to create an outlet that was not only scientifically accurate, but we also hoped it would be enjoyable to listen to,” Arcand says. "It was about making sure the instruments played together in symphony."
But discordant sounds can also be educational, Malec says. She points to the new sonication of the rest of the supernova Cassiopeia A: the sonication traces chemical elements along this large plume of celestial remains using notes played on string instruments (SN: 19/02/14). Those notes make for good harmony, but they can be hard to distinguish, Malec says. “I would choose very different instruments” to make ear tracking easier: perhaps a violin paired with a trumpet or an organ.
While sonication is a valuable tool for the public to take an interest in astronomy, it also has untapped potential to help professional astronomers analyze data, says Wanda Diaz-Merced, an astronomer who is also at the Harvard-Smithsonian Center for Astrophysics but did not participate in the project (SN: 22/10/14).
Astronomers, including Diaz-Merced, blind, have used sonications to study stars, the solar wind, and cosmic rays. And in experiments, Diaz-Merced showed that sighted astronomers can better choose the signals in data sets by analyzing sound and visual information together rather than relying solely on vision.
Still, efforts to sonicate astronomy datasets for research have been rare. Making data sonication a common research method would not only break down barriers to astronomy research, but could also lead to many new discoveries, she said.