Last Week You Saw the First Image of Sagittarius A – Now You Can Hear It

Astronomy is known for its magnificent sights, but NASA’s Chandra X-ray Observatory team has been titillating human hearing by converting data collected by observatories from cosmic objects into sonification. Sagittarius A*, the supermassive black hole at the heart of the Milky Way, is the most recent object to receive this treatment. The Event Horizon Collaboration reported last week that it has captured the first direct photograph of the spectacular object at the center of our galaxy. And you can now hear it.

Volume differences follow variations in brightness in the material near Sagittarius Aevent *’s horizon (pronounced A-star, the star denoting a black hole). The event horizon is the black hole’s “surface,” or point of no return. Light, for example, can never leave the black hole once it travels through it. Higher frequencies signify material closer to the black hole, which flows quicker than material further away. The sonification is designed to produce a 3D stereo sound that may be heard straight on before moving clockwise and from one ear to the next.

About 27,000 light-years distant is Sagittarius A*. It has a mass of approximately 4.1 million Suns. Black holes are extremely dense, despite their size. The entire picture would fit within Mercury’s orbit. A telescope the size of Earth was required to see something so (relatively) little so far away. 

We don’t have one, but we can use a smart physics technique to allow a bunch of ground-based telescopes all across the world to work together and behave like one, which is what the Event Horizon Telescope cooperation is all about. Its accuracy is so good that it’s comparable to seeing a doughnut on the Moon’s surface.

Sagittarius A*, the supermassive black hole at the center of our galaxy, the Milky Way, has never been seen before. We now know what this cosmic monster in our area of the universe looks like thanks to the Event Horizon Telescope collaboration, which provided the first-ever photograph of a black hole. NASA’s Chandra observatory provided X-ray data to accompany the historic photograph. Together, they provide incredible new information on the Milky Way’s most significant occupant. Among them, the researchers determined that Sagittarius Aspin *’s axis is practically squarely pointed towards Earth. The Astrophysical Journal Letters has published the findings of the EHT team.