‘Point of no return’ found
Using a continent-spanning telescope, an international team of astronomers has peered to the edge of a black hole at the center of a distant galaxy. For the first time, they have measured the black hole’s “point of no return” — the closest distance that matter can approach before being irretrievably pulled into the black hole. A black hole is a region in space where the pull of gravity is so strong that nothing, not even light, can escape. Its boundary is known as the event horizon. “Once objects fall through the event horizon, they’re lost forever,” says lead author Shep Doeleman, assistant director at the MIT Haystack Observatory and research associate at the Harvard-Smithsonian Center for Astrophysics (CfA). “It’s an exit door from our universe. You walk through that door, you’re not coming back.” The team examined the black hole at the center of a giant elliptical galaxy called Messier 87 (M87), which...