A black hole skulking in the shadows 600 million light-years away in space gave itself away with a dazzling flash, the light of a star it had just gnashed and eaten.
Using NASA's Hubble Space Telescope and other observatories, astronomers found the cosmic object in an unexpected place. Rather than sitting dead center in its galaxy like most supermassive black holes, this one was thousands of light-years away from the core — 2,600, in fact.
What's more, there is another enormous black...