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Using a distant quasar as a beacon, researchers identified the tiny, turbulence-driven ripples imprinted on the quasar’s radio signal as it passed through a particularly chaotic region of the Milky Way.
Cambridge, MA (May 13, 2026) — Astronomers led by the Center for Astrophysics | Harvard & Smithsonian (CfA) have made the first direct detection of turbulence distorting light in the interstellar medium. The findings will help scientists achieve clearer imaging of the supermassive black hole at the center of the Milky Way Galaxy.
The article was published today in The Astrophysical Journal Letters.
The space between stars in our galaxy, known as the interstellar medium, is churning with clouds of ionized gas and electrons. When waves of radio light from distant objects pass through this turbulent material, they are bent and distorted in the same way heat haze rising above a fire distorts our view of everything behind it.
That distortion has long allowed astronomers to infer that the turbulence exists, but understanding its structure has remained out of reach until now.
To measure the turbulence, astronomers set their sights on quasar TXS 2005+403, a bright radio source powered by a supermassive black hole that is located roughly 10 billion light-years away from Earth in the constellation Cygnus. As radio light from the quasar travels toward Earth, it passes through the Cygnus region of the galaxy, one of the most turbulent and strongly scattering environments in the Milky Way, causing the radio waves to be deflected and distorted.
“Most of what we see in the radio data isn’t coming from the quasar itself, it’s coming from the scattering caused by the turbulence in this region of the Milky Way,” said Alexander Plavin, an astronomer at the CfA’s Black Hole Initiative and lead author of the new paper.
“That scattering and the distortions that come with it are what allows us to study the turbulence and better understand and infer its structure.”
To get a better look at the effects of turbulence on light from the quasar, scientists analyzed nearly a decade of archival observations from the U.S. National Science Foundation’s Very Long Baseline Array (NSF VLBA). Operated by NSF’s National Radio Astronomy Observatory (NSF NRAO), the NSF VLBA is a network of ten radio telescopes spread across the country.
Scientists expected that when radio light from TXS 2005+403 passed though the Milky Way, it would spread out into a smooth blur and fade away. Instead, they found persistent, distinct patterns, producing structured, patchy distortions in the light that could only have come from turbulence. “The most distant pairs of telescopes should not have seen the quasar image, but to our surprise, they clearly detected its signal, or faint glow,” Plavin said. “It can’t be explained by simple blurring or by the quasar itself, and it behaves the way turbulence is expected to, which is how we know we’re seeing the effects of interstellar turbulence.”
That distortion has long allowed astronomers to infer that the turbulence exists, but understanding its structure has remained out of reach until now.
To measure the turbulence, astronomers set their sights on quasar TXS 2005+403, a bright radio source powered by a supermassive black hole that is located roughly 10 billion light-years away from Earth in the constellation Cygnus. As radio light from the quasar travels toward Earth, it passes through the Cygnus region of the galaxy, one of the most turbulent and strongly scattering environments in the Milky Way, causing the radio waves to be deflected and distorted.
“Most of what we see in the radio data isn’t coming from the quasar itself, it’s coming from the scattering caused by the turbulence in this region of the Milky Way,” said Alexander Plavin, an astronomer at the CfA’s Black Hole Initiative and lead author of the new paper.
“That scattering and the distortions that come with it are what allows us to study the turbulence and better understand and infer its structure.”
To get a better look at the effects of turbulence on light from the quasar, scientists analyzed nearly a decade of archival observations from the U.S. National Science Foundation’s Very Long Baseline Array (NSF VLBA). Operated by NSF’s National Radio Astronomy Observatory (NSF NRAO), the NSF VLBA is a network of ten radio telescopes spread across the country.
Scientists expected that when radio light from TXS 2005+403 passed though the Milky Way, it would spread out into a smooth blur and fade away. Instead, they found persistent, distinct patterns, producing structured, patchy distortions in the light that could only have come from turbulence. “The most distant pairs of telescopes should not have seen the quasar image, but to our surprise, they clearly detected its signal, or faint glow,” Plavin said. “It can’t be explained by simple blurring or by the quasar itself, and it behaves the way turbulence is expected to, which is how we know we’re seeing the effects of interstellar turbulence.”
Plavin added that the scattering properties along this line of sight through the galaxy remain persistent over time.
The findings have significant implications for future astronomical research. The turbulence detected here exists at scales roughly the size of our solar system. Understanding it helps explain how energy moves through the galaxy and how gas behaves before collapsing to form new stars.
The findings may also directly inform efforts to sharpen images of black holes. The Event Horizon Telescope's images of Sagittarius A*, the supermassive black hole at the center of the Milky Way, are degraded by this same interstellar scattering. Studying how turbulence scatters radio light over time and different frequencies provides a path toward removing its effects from those images.
The team has begun a follow-up observing campaign with the NSF VLBA running through 2026, with an aim to measure the specific properties of the screen created by this turbulence and track how it changes as the gas moves relative to Earth.
The findings may also directly inform efforts to sharpen images of black holes. The Event Horizon Telescope's images of Sagittarius A*, the supermassive black hole at the center of the Milky Way, are degraded by this same interstellar scattering. Studying how turbulence scatters radio light over time and different frequencies provides a path toward removing its effects from those images.
The team has begun a follow-up observing campaign with the NSF VLBA running through 2026, with an aim to measure the specific properties of the screen created by this turbulence and track how it changes as the gas moves relative to Earth.
About the Center for Astrophysics | Harvard & Smithsonian
The Center for Astrophysics | Harvard & Smithsonian is a collaboration between Harvard and the Smithsonian designed to ask, and ultimately answer, humanity's greatest unresolved questions about the nature of the universe. The CfA is headquartered in Cambridge, MA, with research facilities across the U.S. and around the world.
