Astronomers Watch a Black Hole Wake Up in Real Time

You never know when a central supermassive black hole is going to power up and start gobbling matter. Contrary to the popular view that these monsters are constantly devouring nearby stars and gas clouds, it turns out they spend part of their existence dormant and inactive. New observations from the European Space Agency's XMM-Newton spacecraft opened a window on the "turn on event" for one of these monsters in a distant galaxy.