And you thought this was about Robin. For the first time, scientists have peered to the edge of a colossal black hole and measured the point of no return for matter. A black hole has a boundary called an event horizon. Anything that falls within a black hole's event horizon â€” be it stars, gas, or even light â€” can never escape. "Once objects fall through the event horizon, they're lost forever," Shep Doeleman, assistant director of the MIT Haystack Observatory and research associate at the Smithsonian Astrophysical Observatory, said in a statement Thursday (Sept. 27). "It's an exit door from our universe. You walk through that door, youâ€™re not coming back." Although the event horizon is an imaginary line that's impossible to observe, astronomers have imaged the region around a giant black hole at the center of a distant galaxy, and measured, for the first time, the closest stable orbit in which matter can circle the black hole. The findings were reported today in the journal Science. The supermassive black hole in question lies at the center of the galaxy M87, which is about 50 million light-years from our own Milky Way. This behemoth black hole contains the mass of 6 billion suns.