Albert Einstein's theory of general relativity has aced another test. Following nearly 3 decades of monitoring, researchers have detected a subtle shift in the orbit of the closest known star to the supermassive black hole at the center of the Milky Way—and the movement matches Einstein's theory precisely.
The star, known as S2, follows an elliptical 16-year orbit. It made a close approach—within 20 billion kilometers—to our black hole, Sagittarius A*, last year. If Isaac Newton's classic description of gravity holds true, S2 should then continue along exactly the same path through space as on its previous orbit. But it didn't.