If there’s one certainty in astronomy, it’s that you can never be certain about anything. And that’s definitely the case with the recent discovery of a black hole in a region thought to be inhospitable to such objects.

The discovery, reported in the Jan. 4 issue of the journal Nature, is of a black hole inside a star cluster within NGC 4472, an elliptical galaxy approximately 50 million light-years away from Earth. The discovery goes against previous thinking, which predicted that a black hole probably couldn’t exist inside a star cluster, where gravitational interactions between black holes would eject any black hole from the cluster. Scientists believe this black hole may have survived because it paired up with a star, which would stabilize and keep it in the cluster. (It is thought that black holes within a cluster usually fall to the middle of the cluster, and pair up with another black hole or a star.) Or, the black hole may be so massive that it resisted being rejected.

The discovery is but one more shift in our thinking about black holes, an idea that dates back to the 1784, when English geologist John Mitchell proposed the idea of a body so massive that nothing, not even light, could escape it. In 1796, mathematician Pierre Simon-LaPlace suggested the same idea, although the concept didn’t then gain widespread acceptance. When Albert Einstein introduced his general theory of relativity, Karl Schwarzschild discovered a solution to Einstein’s equation that suggested such an object. By the 1930s, thanks to the work of scientists like Robert Oppenheimer, Volkoff, and H. Snyder, the idea was more thoroughly developend and gained more widespread support.

It was the work of Stephen Hawking and Roger Penrose in 1970 that brought the idea of black holes into the mainstream. The term “black hole” was coined in 1967 by theoretical physicist John Archibald Wheeler in his lecture “Our Universe: the Known and Unknown .”

Though black holes are difficult to observe, and therefore prove, several other recent discoveries lend support to the concept. In 2004, astronomers detected 31 possible supermassive black holes, and suggested that there are from two to five times as many supermassive black holes are previously believed.

Black holes are one of the greatest unknown elements in astronomy, but this latest discovery, coupled with decades of theoretical and observational work, takes science another step closer to unraveling these mysterious objects.