In what is being heralded as a momentous and long-awaited development in scientists’ search to understand some of the most mysterious aspects of our universe, astronomers for the first time have captured a photo of a black hole, an international consortium of scientists announced in simultaneous press conferences around the world Wednesday.
OK, it’s not exactly a photo of a black hole. As remnants of collapsed stars, black holes are so dense that their gravitational forces prevent all matter and even light from escaping, which means that they cannot themselves be photographed, as they are unseeable. So this photo doesn’t tell astronomers everything they would like to know about the objects. But it does show the halo of super-heated dust and gas that swirls around the black hole at near the speed of light before being sucked in (or, more technically, it shows the effects the black hole’s gravity has on that matter, as the gravity warps the shape of space-time itself, deflecting light and creating a shadow). Beyond producing a cool-looking image, the data will help scientists learn about how gravity and light contort just at the black hole’s edge.
According to the Guardian, they have already learned about the nature of the light’s bend just at the black hole’s event horizon—the point after which no light can escape. And the photo appears to confirm some of their understanding as to how the physics would work: The particles on one side of the disk appear brighter because they are being shot in our direction as the disk of gas and dust rotates.
This particular black hole is an extremely massive one—it has a mass of about 6.5 billion of our suns.* It sits at the center of the galaxy Messier 87, roughly 55 million light-years away, which means the image is actually of the black hole 55 million years ago. Despite its enormous size, scientists had worried we would not be able to create a telescope powerful enough to see something so far away.
The breakthrough came when a group of more than 200 scientists collaborated across eight of the planet’s most powerful radio telescopes, making up the Event Horizon Telescope. They waited for a clear sky to happen simultaneously in all eight locations around the world, syncing up each telescope with absolute precision using atomic clocks and supercomputers, and combining and comparing observations from each different telescope. According to the Guardian, the photo was taken in April 2017, and one reason for the delay was that collaborators in Antarctica had to wait until the end of Antarctic winter to send over their data.
The image now represents the strongest evidence yet for the existence of black holes—something first theorized by Albert Einstein (the detection in 2016 of gravitational waves made by two colliding black holes was another particularly exciting piece of evidence). Scientists are hoping that the data taken by the EHT will prove fertile for more discovery. In the meantime, if you’re disappointed by the blurriness of the image, you might not have to wait until the next multi-continent scientific endeavor: According to NBC News, one of the major goals for the group is to use the data to make sharper images.
Correction, April 10, 2019: This post originally misstated the mass of the black hole. It is 6.5 billion times that of the sun, not 6.5 million times.