Data Sonification: Sounds from Around the Milky Way

Explore Solos

The center of our Milky Way galaxy is too distant for us to visit in person, but we can still explore it. Telescopes give us a chance to see what the Galactic Center looks like in different types of light. By translating the inherently digital data (in the form of ones and zeroes) captured by telescopes in space into images, astronomers create visual representations that would otherwise be invisible to us.

But what about experiencing these data with other senses like hearing? Sonification is the process that translates data into sound, and a new project brings the center of the Milky Way to listeners for the first time. The translation begins on the left side of the image and moves to the right, with the sounds representing the position and brightness of the sources. The light of objects located towards the top of the image are heard as higher pitches while the intensity of the light controls the volume. Stars and compact sources are converted to individual notes while extended clouds of gas and dust produce an evolving drone. The crescendo happens when we reach the bright region to the lower right of the image. This is where the 4-million-solar-mass supermassive black hole at the center of the Galaxy, known as Sagittarius A* (A-star), resides, and where the clouds of gas and dust are the brightest.

Users can listen to data from this region, roughly 400 light years across, either as "solos" from NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope, or together as an ensemble in which each telescope plays a different instrument. Each image reveals different phenomena happening in this region about 26,000 light years from Earth. The Hubble image outlines energetic regions where stars are being born, while Spitzer's infrared image shows glowing clouds of dust containing complex structures. X-rays from Chandra reveal gas heated to millions of degrees from stellar explosions and outflows from Sagittarius A*.

In addition to the Galactic Center, this project has also produced sonified versions of the remains of a supernova called Cassiopeia A, or Cas A, and the "Pillars of Creation" located in Messier 16.

Welcome to Emily Zhang, Chandra Summer Intern

Emily Zhang
Emily Zhang on the Athabasca Glacier in Banff National Park in Canada. Emily traveled there in the summer of 2018, coincidentally just after finishing her first research project at the CfA! Credit: Emily Zhang

We are delighted to introduce Emily Zhang, who is working as a summer intern in the Chandra X-ray Center at the Center for Astrophysics. Emily is spending half of her time working on astronomy research with Dr Pat Slane and half working on science communication with us in the Chandra Communications and Public Engagement group. She is an undergraduate at Columbia University majoring in astrophysics and (hopefully) concentrating in political science. We asked Emily some questions about her background and interests in astronomy and science communication.

How did your interest in astronomy develop?

I remember watching the TV show Nova with my parents when I was little, and thinking that outer space looked so beautiful and so different from the rest of the world I knew. I also remember going on trips to my local planetarium (the Hayden Planetarium at the Museum of Science in Boston) growing up, and coming out of their shows crying at how big the universe was. I have a vivid memory of checking out a book on black holes for kids from the library, and reading that if you went through a black hole, you could end up in a new universe with up to 11 dimensions. This was not something I understood at all as a 4th grader, but I was impressed.

Behind the Scenes with the Image Makers

2019 Chandra Archive Image Collection
2019 Chandra Archive Collection
Credit: Enhanced Image by Judy Schmidt (CC BY-NC-SA) based on
images provided courtesy of NASA/CXC/SAO & NASA/STScI.

It is both an art and a science to make images of objects from space. Most astronomical images are composed of light that humans cannot detect with their eyes. Instead, the data from telescopes like NASA’s Chandra X-ray Observatory are “translated,” so to speak, into a form that we can understand. This process is done following strict guidelines to ensure scientific accuracy while trying to achieve the highest levels of aesthetics possible.

Over the two decades of the Chandra mission, we have had many talented people who have been involved with making our publicly-released images. We interviewed our current team and share some of their answers to questions posed to all of them below. Kim Arcand is Chandra’s visualization lead and has been with the mission since before launch; Nancy Wolk has been involved with Chandra’s data analysis, software, and spacecraft science operations before joining the image processing team; Lisa Frattare spent years making images from the Hubble Space Telescope before switching career gears but continues to lend her expertise part-time to Chandra’s efforts; Judy Schmidt is a citizen scientist who spends some of her free time using public data to make gorgeous images of space, including those featured in our latest release.

Exploring New Paths of Study with Chandra

Chandra spacecraft image
Illustration: Chandra X-ray Observatory

We make progress in astrophysics in a variety of ways. There is the sort that starts along a defined path, driven by meticulous proposals for telescope time or detailed science justifications for new missions. The plan is to advance knowledge by traveling further than others, or clearing a broader path. And then there are others.

A big mission like NASA's Chandra X-ray Observatory begins with plans for investigation along a slew of different directions and lines of study. At the time of Chandra's launch on July 23rd, 1999, scientists thought these paths would mainly follow studies of galaxy clusters, dark matter, black holes, supernovas, and young stars. Indeed, in the last 20 years we've learned about black holes ripping stars apart (reported eg in 2004, 2011 and 2017), about a black hole generating the deepest known note in the universe, about dark matter being wrenched apart from normal matter in the famous Bullet Cluster and similar objects, about the discovery of the youngest supernova remnant in our galaxy, and much more.

Gearing Up for Chandra’s 20th


Beginning in less than a month, we will be celebrating the 20th anniversary of the launch of NASA’s Chandra X-ray Observatory into space. To get Chandra-philes (Chandra-ites?) ready and bring new ones into the fold, we have been busy here at the Chandra X-ray Center preparing a slew of activities, products, and more to usher in our favorite X-ray telescope’s third decade of operation. Here are just a few of the things to look forward to this year:

  • Launching with yet more content soon, a special section of the website devoted to the Chandra’s 20thanniversary. (Keep an eye on the calendar of events list for potential opportunities in your area to speak with Chandra scientists.)
  • A collection of new Chandra images will be released twenty years to the day – July 23rd– that the Space Shuttle Columbia launched Chandra into orbit.

New Chandra Operations Control Center Opens

Chandra's New Operations Control Center
Chandra's New Operations Control Center

A new state-of-the-art facility that will operate NASA's Chandra X-ray Observatory has opened. This new Operations Control Center, or OCC, will help Chandra continue its highly efficient performance as NASA's premier X-ray observatory.

As the name suggests, the OCC controls the operation of the Chandra spacecraft while it is in orbit, as scientists and engineers design plans for efficiently and safely observing its targets.

Two years before Chandra's launch into space in 1999, NASA awarded the Smithsonian Astrophysical Observatory a contract to establish the first OCC as part of the Chandra X-ray Center, under the direction of NASA's Marshall Space Flight Center. Northrup Grumman was and continues to be a prime contractor for Chandra, employing many staff members at the OCC.

Elaine Jiang

Elaine Jiang
Elaine Jiang

My name is Elaine Jiang, and I am a current senior at Brown University studying computer science. I spent the first nine years of my life in Suffern, New York, and the following nine years in Shanghai, China, before coming back to the states for college. In terms of technology, I’m interested in artificial intelligence (AI), virtual reality, and ethical software design. Outside of computer science, I can be found teaching and mentoring students in science, technology, engineering, and math (STEM), going to spin classes, and exploring Providence's delicious brunch options.

My parents have always encouraged me to explore my interests in science and technology. When we lived in upstate New York, one of my favorite memories was going to the Museum of Natural History with my dad every year, looking at fossils and animals, and jotting down notes in my “science journal.” I’m really grateful to have been exposed to science at a young age, as this certainly led to my interest in becoming a STEM major.

During the summer after my sophomore year in college, I had the opportunity to do research with Tom Sgouros, who managed Brown’s Yurt Ultimate Reality Theatre. Tom introduced me to Kim Arcand from the Chandra X-ray Observatory, and we worked with her to render a three-dimensional model of supernova remnant Cassiopeia A into virtual reality. It’s been an incredibly rewarding experience, and I’m excited to see what we do next.

Chandra to Continue Operations During US Government Shutdown

Chandra Spacecraft

NASA has designated Chandra as "excepted" during the Government shutdown and requested that SAO continue Chandra X-ray Center (CXC) operations. Since NASA is unable to provide funding during the shutdown, the Smithsonian Institution has agreed to advance funding to continue science and mission operations through mid-March, as necessary.

A Hero of the Heroic Age of Astronomy

Riccardo Giacconi (1931-2018)

Riccardo Giacconi
Riccardo Giacconi speaking at a Chandra Symposium in 2003. Credit: NASA/MSFC

Riccardo Giacconi, the "Father of X-ray Astronomy," Nobel prize-winner, and one of the most influential figures of modern astrophysics, has died at the age of 87.

Giacconi was born in Genoa Italy on October 6, 1931. He spent most of his life until 1956 in Milan, where he obtained a Ph.D. in physics from the University of Milan, working under the direction of noted cosmic ray physicist Giuseppe Ochialini. Giacconi subsequently worked as an assistant professor at the University of Milan before emigrating to the United States to work for R.W. Thompson as a Fulbright Fellow at Indiana University.

From Indiana he moved to Princeton where he met and worked with Herbert Gursky, also a post-doctoral fellow. According to Giacconi, "We built equipment, worked like fiends, analyzed data, and declared failure." When his Fulbright fellowship expired, Giacconi moved to American Science and Engineering (AS&E) in Cambridge, MA, a startup formed by Martin Annis, an ex-student of Bruno Rossi of the Massachusetts Institute of Technology (MIT). At that time AS&E was primarily involved in military space research.

Remembering Riccardo Giacconi, X-Ray Astronomy Pioneer

Courtesy of

Riccardo Giacconi
Riccardo Giacconi (Credit: R.K. Morris)

NASA is saddened to note the passing of Riccardo Giacconi, who had a long and illustrious career with the agency.

“Riccardo set the standard for the way that NASA astrophysics is done, by involving the entire astronomy community in space missions via robust Guest Observer programs. We continue to benefit from his foresight,” said Paul Hertz, Director of Astrophysics at NASA.

Giacconi’s early sounding rocket work opened the field of X-ray astronomy, in which NASA continues to be a world leader. He led the sounding rocket experiment that discovered the first two non-solar cosmic X-ray sources: the X-ray background and the neutron star Scorpius X-1. This breakthrough led Giacconi to propose to NASA the Small Astronomy Satellite-A or SAS-A, renamed “Uhuru” at launch. The satellite produced the first catalog of cosmic X-ray sources.

He went on to develop the first focusing X-ray telescope, the Einstein Observatory, and then to write the proposal for NASA's Chandra X-ray Observatory. Chandra continues to operate today, and is the most sensitive X-ray observatory ever developed.

NASA was delighted when Giacconi won the Nobel Prize in Physics in 2002 “for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources.”

Giacconi was also the first permanent director of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. Under his leadership from 1981 to 1993, STScI developed the expertise and capabilities to direct the science mission of the Hubble Space Telescope.


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