As described in today’s Nature, a couple of guys over at the National Optical Astronomy Observatory in Tucson, Arizona have spotted a galaxy that appears to have two, supermassive black holes at its core. The two holes are pretty big: the smaller one is around 10 million solar masses and the big one weighs in at about a billion. The little one is orbiting at a third of a light year from its mate, and it gets around once every 100 years. In astronomical terms, that is incredibly fast.

This is something people have expected to see for a long time. Astronomers believe that today’s galaxies formed from the mergers of earlier ones, and along the way, you would expect two black holes two be orbiting one another. But until now, nobody has actually spied a binary black hole system. It’s a find big enough to attract quite a bit of coverage.

The way in which astronomers found this galaxy is just as remarkable. Instead of using some super-powerful telescope, they sifted through a giant database of the night sky, known as the Sloan Digital Sky Survey. After checking some 17,500 distant galaxies, known as quasars, they found one that appeared to fit the bill.

Most astronomers agree that this sort of digital astronomy is the way forward, and more surveys are now in the works. You can hear one of the authors, Todd Boroson, talking all about this week’s black hole discovery on Nature’s podcast.

Credit: NOAO