Descriere : In the century since Einstein predicted the existence of black holes in his theory of gravity, astrophysicists have turned up overwhelming evidence for the things. They’ve observed the push and pull of black holes on the orbits of nearby stars and planets. They’ve heard the vibrations, or gravitational waves, resonating from black holes colliding. But they’d never glimpsed a black hole face to face—until now. On Wednesday, astrophysicists announced they had captured the first-ever image of a black hole.
The picture, taken over five days of observations in April 2017 using eight telescopes around the world by a collaboration known as the Event Horizon Telescope, depicts luminous gas swirling around a supermassive black hole at the center of M87, a galaxy 54 million light-years away. Past the bright lights, though, is the black hole’s telltale feature: its event horizon. The event horizon is the edge of the spacetime abyss, where gravity is so strong that no light can escape from it. “It’s the point of no return,” says Feryal Özel of the University of Arizona, who is a member of the EHT collaboration. In the image, it manifests itself as the “sudden absence of light,” she says.
This black hole is about 6.5 billion times the mass of the sun. Still, it’s tiny from a vantage point on Earth, less than 50 microarcseconds wide in the sky, which makes it about as hard to see as a donut placed on the moon. It took eight different telescopes to image it. The telescopes collected observational data that was synced with the precision of a billionth of a second.
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Sursa : wired.com
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