A team of astronomers using the Event Horizon Telescope—a group of eight radio telescopes scattered across the planet and operating together in a way that makes them behave as a single Earth-sized instrument—has captured enough information to produce the first image of a black hole. Or, at least, the material around the black hole.
Black holes, by definition, are black. Resulting from the explosion of massive stars, these leftover remnants have collapsed under their own weight until they’ve become a point of infinite density—a puncture in spacetime. Surrounding that singularity is a region in which gravity is so great, not even light can escape. When black holes first emerged from calculations based on relativity early in the 20th century, scientists expected them to be just that—tiny absences of light that would be almost impossible to spot, even if they were relatively close at hand. However, scientists have since determined that the area around a black hole is anything but dark. As matter spirals down toward the crushing gravity well, it accelerates. And accelerates. And gets very, very energetic. The result is a halo of energy blasting away from the edges of the black hole.
The black hole in this groundbreaking image isn’t just any black hole; it’s what’s known as a supermassive black hole. These giants are thought to lie at the hearts of most galaxies, including our own. The imaged black hole is in the center of galaxy Messier 87, which is a whopping 55 million light-years from Earth. That might not make this black hole seem like a great candidate for the first to be imaged, but in this case “supermassive” doesn’t even seem adequate, as the black hole is estimated to be 6.5-billion times more massive than our sun. It’s been sitting at the center of its galaxy for a long time. Eating.
The teams behind the discovery are holding a series of international press conferences around the world today, at locations tied to the EHT telescope sites. They’re also providing a series of six connected reports to be published in a special issue of Astrophysical Journal Letters.
NSF animation of what it would be like to visit the black hole at the center of Messier 87.