The galaxy Messier 77 (M77) is famous for its super-active nucleus that releases enormous energy across the electromagnetic spectrum, ranging from x-ray to radio wavelengths. Yet, despite its highly active core, the galaxy looks like any normal quiet spiral. There's no visual sign of what is causing its central region to radiate so extensively. It has long been a mystery why only the center of M77 is so active. Astronomers suspect a long-ago event involving a sinking black hole, which could have kicked the core into high gear.