Massive, crushing, powerful, and invisible—black holes have long occupied a corner of the human imagination. Now, though, astronomers have released what they’re saying is an actual image of one from faraway in space.
“We have seen what we thought was unseeable,” said Shep Doeleman, director of the international team behind the image. “We have seen and have taken a picture of a black hole.”
Researchers on the Event Horizon Telescope project made the announcement today (April 10) at the National Press Club in Washington, DC. The team has operated by linking up giant radio dishes from across the world, which has created a virtual telescope that’s about the size of Earth itself. The idea was that in creating such a network, they could generate the enormous amount of magnifying power needed to collect enough electromagnetic and radio waves to create an image of an area around a distant black hole.
Why it’s hard to see
It was an elusive goal from the get-go. The target is invisible to the naked eye. Black holes are regions of space believed to have been formed when massive dying stars eventually collapse, leaving behind a space with such an immense gravitational power that even particles of light can’t escape their inward pull. The idea is that if something goes into a black hole, it gets shredded up, heated up, and then expelled.
In this historic case, the image was made possible because tiny photons are being sucked into the black hole in the Messier 87 galaxy, which is 53.49 million light years from Earth. Getting sucked into a black hole was described by the scientists as being plunged into most extreme environment in the known universe. The photons make their way into the center of the hole at light speed, transforming into 100 billion-degree plasma that’s then expelled outward from the blackhole in massive jet streams, one of which is pointed almost directly toward Earth.
Back on Earth, the network of telescopes collected the data coming toward them from the black hole jet stream. It was an enormous amount of data, too, about five petabytes—about the size as 5,000 years of MP3 music files. Because the size of the data was so immense, the hard drives on which they were kept were flown to a central location to be analyzed. Transmitting the files via the internet simply would have been too slow.
From there, scientists worked to create the single image that was shared today. It’s the size of just a few kilobytes. And that image helps broaden our understanding of the role black holes likely play. As it turns out, the jet streams expelled from black holes are immensely important when considering how galaxies and clusters of galaxies are formed and shaped, said Sera Markoff, an astrophysicist and member of the team from the University of Amsterdam.
“When a black hole is activated by gravitationally capturing material…black holes temporarily become the most powerful engines in the universe,” Markoff said. “Enormous fountains of magnetized material being sprayed out at nearly the speed of light.”
The persistence of an idea
The first notions of black holes began to creep into scientific literature in the late 1700s, when John Mitchell, an English clergyman, proposed the idea in a letter. His thought was built upon by Albert Einstein, using the theory of general relativity; Robert Oppenheimer, and countless other scientists. In 2015, the Event Horizon Telescope team successfully observed gravitational waves around a black hole, which provided the best evidence of their existence. In many ways, the findings and the subsequent image supports the theory Einstein first explored as while working as a patent reviewer in Switzerland.
“I do spend time thinking about how it is that someone could have sat down in a patent office some 100 years ago and come up with the theory,” Markoff said.
Asked how the news of the final image rippled throughout the team of about 200 scientists on the Event Horizon Telescope project, Doeleman paused to think for a moment.
“There was a great sense of relief to see this, but also surprise,” he said. “When you work in this field for a long time you get used to seeing intermediate results. It was just astonishment, I think. And wonder.”