![]() ![]() Part of the reason it took so long was the global devastation of the COVID pandemic. The scientists then spent years analyzing the raw data and converting them into an image. In April 2017 the EHT collaboration spent several nights pointing that virtual instrument at Sagittarius A* and other supermassive black holes. The EHT captured images of this shadow using a technique called very long baseline interferometry (VLBI), which combines radio observatories on multiple continents to form a virtual Earth-size telescope, an instrument with the highest resolution in all of astronomy. But they warp spacetime around them so severely that, when they are illuminated by glowing streams of infalling matter shredded in their gravitational grip, they cast a “shadow.” The shadow is about two and a half times larger than a black hole's event horizon, the boundary in spacetime through which nothing that passes can ever return. Sagittarius A* is our own private supermassive black hole, the still point around which our galaxy revolves.īlack holes trap everything that falls in, including light, so they are, in a very real sense, unseeable. ![]() It wasn't the first picture of a black hole this collaboration had captured-that was the iconic image of M87*, which they revealed in April 2019. This past spring, however, the astronomers behind the Event Horizon Telescope (EHT) settled the matter by unveiling the first image of a supermassive black hole at the center of the Milky Way. For example, when astronomers Reinhard Genzel and Andrea Ghez shared a portion of the 2020 Nobel Prize in Physics, their citation specified that they were awarded for “the discovery of a supermassive compact object at the centre of our galaxy,” not the revelation of a “black hole.” The object is known as Sagittarius A* (“Sagittarius A star”). ![]() Scientists have long thought that only a supermassive black hole could explain the stars' movements, but until this year, they hesitated to say that outright. This is a place where stars slingshot around apparently empty space at an appreciable fraction of the speed of light. Deep in the heart of the Milky Way, strange things happen. ![]()
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