Discover the first-ever photo of a black hole in the Milky Way

Scientists have long speculated about the existence of black holes. Albert Einstein originally predicted them in his theory of relativity and Roger Penrose developed mathematical formulas to explain their formation. But it wasn’t until 2019 that we saw our first photographic evidence of a black hole, taken in the M87 galaxy using the Event Horizon Telescope (an international collaboration of radio telescopes). Now, that same telescope has been used to photograph Sagittarius A* (Sgr A*), a giant black hole located right in the center of our own Milky Way.

The image, released earlier this week, shows an ultra-hot donut of gas surrounding a black hole, or Sgr A*’s event horizon.

Related: How Scientists Saw the ‘Invisible’ and Captured the First Image of a Black Hole

Photo confirms years of speculation

The composite photo, which is the work (and victory) of more than 300 researchers from 80 international institutions, is the very first photo of Sgr A*, ever taken.

For some time, scientists have suspected its existence and preemptively name it Sgr A*. Prior to the discovery, researchers had predicted its size and shadow based on the movements of nearby stars. Sgr A* is the closest supermassive black hole to Earth, 25,640 light-years away.

The dark spot in the center of the image is the black hole’s event horizon. EHT cooperation

why is it important

Although Sgr A* is four million times larger than our sun, it is still considered tiny in black hole jargon. Despite its relatively small size, it was still difficult for scientists to get a good view, due to other objects crossing the path of observation.

However, the fact that they now have a vision of it is significant. The black hole, surrounded by a ring of hydrogen gas, is located at the center of the Milky Way. And studying it could provide clues to how the galaxy formed and how it might evolve.

“Through this imagery, we are not only learning about our galaxy, but also how gas acts around black holes more generally, confirming models made here on Earth,” writes Grace Malato of the National Science Foundation (NSF). , one of the funders of the project.

sagittarius a photo
The final image (top) is a composite of many observations. EHT cooperation

What you see

The image consists of a fiery orange ring surrounding a dark spot. This location is what scientists understand to be Sgr A*, thus proving its existence. The image is the result of five years of supercomputer data processing, which included more than 80 million CPU hours on the NSF-backed Frontera supercomputer and an additional 20 million hours on the OpenScienceGrid.

“Wide collaboration was key because each telescope has a different view of its place on Earth and therefore provides a unique contribution to the dataset, which combines for a more complete view of Sgr A*,” notes Malato.

So what’s the next step? The possibilities are many, but include finding even better images and, perhaps, videos. It is also hoped to deploy more radio telescopes around the world, allowing scientists to better see more distant objects.

Jack C. Nugent