Astronomers reveal first image of black hole at Milky Way's centre

An international team of astronomers on Thursday unveiled the first image of a supermassive black hole at the centre of our own Milky Way galaxy — a cosmic body known as Sagittarius A*.

The image — produced by a global team of scientists known as the Event Horizon Telescope (EHT) Collaboration — is the first, direct visual confirmation of the presence of this invisible object, and comes three years after the very first image of a black hole from a distant galaxy.

“For decades, we have known about a compact object that is at the heart of our galaxy that is four million times more massive than our Sun,” Harvard University astronomer Sara Issaoun told a press conference in Garching, Germany, held simultaneously with other media events around the world.

“Today, right this moment, we have direct evidence that this object is a black hole.”

Black holes are regions of space where the pull of gravity is so intense that nothing can escape, including light.

The image thus depicts not the black hole itself, because it is completely dark, but the glowing gas that encircles the phenomenon in a bright ring of bending light.

As seen from Earth, it appears the same size as a donut on the surface of the Moon, Issaoun explained.

“These unprecedented observations have greatly improved our understanding of what happens at the very centre of our galaxy,” EHT project scientist Geoffrey Bower, of Taiwan’s Academia Sinica, said in a statement.

The research results are published in The Astrophysical Journal Letters.

Sagittarius A* — abbreviated to Sgr A*, and pronounced “sadge-ay-star” — owes its name to its detection in the direction of the constellation Sagittarius.

Located 27,000 light years from Earth, its existence has been assumed since 1974, with the detection of an unusual radio source at the centre of the galaxy.

In the 1990s, astronomers mapped the orbits of the brightest stars near the centre of the Milky Way, confirming the presence of a supermassive compact object there — work that led to the 2020 Nobel Prize in Physics.

Though the presence of a black hole was thought to be the only plausible explanation, the new image provides the first direct visual proof.

Capturing images of such a faraway object required linking eight giant radio observatories across the planet to form a single “Earth-sized” virtual telescope called the EHT.

“The EHT can see three million times sharper than the human eye,” German scientist Thomas Krichbaum of the Max Planck Institute for Radio Astronomy told reporters.

“So, when you are sitting in a Munich beer garden, for example, one could see the bubbles in a glass of beer in New York.”

The EHT gazed at Sgr A* across multiple nights for many hours in a row — a similar idea to long-exposure photography and the same process used to produce the first image of a black hole, released in 2019.

That black hole is called M87* because it is in the Messier 87 galaxy.

The two black holes bear striking similarities, despite the fact that Sgr A* is 2,000 times smaller than M87*.