One problem with seeing black holes in space is that they are, well, black. But having inferred the presence of black holes in the universe for decades, NASA scientists may have actually seen one at last. The reason black holes are black is simple: their gravity is so strong that nothing--not even light--can escape them. No light, no image. So Joseph F. Dolan, a scientist at NASAs Goddard Space Flight Center, instead looked at data gathered by the Hubble Space Telescope during an observation of Cygnus XR-1 in 1992. Located about 6,000 light-years from Earth in the summer constellation Cygnus the Swan, Cygnus XR-1 is one of the first black holes ever discovered.

As Dolan found, the Hubble picked up chaotic fluctuations in ultraviolet light, which was emitted by hot gases that spiraled around the compact, but massive black hole and then disappeared. This observation corresponds to current theories on black holes: as matter is pulled towards a black hole, it swirls around the perimeter and is eventually sucked in, much like water going down a drain.

In fact, the telescope collected 1 billion data points during its observation of the black hole, and Dolan admits that this research was like looking for the proverbial needle in a haystack. In all, he only found two examples of the telltale chaotic fluctuations, leading him to state his results with caution: the fluctuations resemble what experts expect to see when matter falls into a black hole, but they could be statistical flukes