【#Tech24H】A research team from the Max Planck Institute for Radioastronomy in Germany has announced that, after 23 years of high-resolution radio observations, they have inferred the presence of two supermassive black holes orbiting each other with a period of approximately 121 days at the center of the galaxy Mrk 501. The distance between them is between 250 and 540 times the Earth-Sun distance. Due to gravitational wave radiation, their orbit will continue to shrink. Theoretical projections indicate that they could merge within as little as a hundred years. This is very likely the first time humanity has observed a supermassive black hole pair that has entered the countdown to merger, providing a precious opportunity to uncover the core mechanisms of galactic evolution.