An international astronomy team released the first image of the supermassive black hole at the center of our galaxy on Thursday, a quiet giant at the heart of the Milky Way.
"What we see is the heart of the black hole, the point of no return," said National Science Foundation chief operating officer Karen Marrongelle, who introduced the Event Horizon Telescope Collaboration result. The find directly confirms the long-held suspicion that a black hole sits at the center of our galaxy and likely at most others.
Called Sagittarius A*, the black hole weighs 4 million times more than the sun. It is surrounded by a heated plasma trillions of degrees in temperature, a donut-shaped halo surrounding its dark "event horizon" that reveals its presence. It sits about 28,500 light-years away (one light-year is about 5.9 trillion miles) in the constellation Sagittarius.
"This is the black hole at the center of our galaxy. That's pretty amazing," said Caltech's Katherine Bouman, a member of the consortium. "What's more cool than seeing the black hole at the center of our galaxy?"
Black holes are collapsed stars with gravity so strong that even light can't escape their gravitational pull. The smallest ones weigh only about four times as much as the sun. Supermassive ones are thought to lurk at the heart of most, if not all, galaxies, the result of stars and gas falling into them over time.
Luckily for our galaxy, said Marrongelle, Sagittarius A* is a relatively gentle black hole, not irradiating the rest of the Milky Way with powerful jets seen in other galaxies. The constellation Sagittarius is in a crowded arm of the galaxy that astronomers had to peer through to see the black hole, making their job more challenging.
A group of over 300 astronomers, the EHTC combined observations from eight telescopes worldwide to capture the picture of Sagittarius A*. The group released the first-ever image of the heavier, more distant supermassive black hole at the center of the M87 galaxy in 2019.