NGC 6240 is a galaxy in which two supermassive black holes are a mere 3,000 light years apart.
These black holes (the two partially overlapping bright point-like sources in the middle) are in such close proximity, scientists think, because they are in the act of spiraling toward each other -a process that began about 30 million years earlier.
It is estimated that the two black holes will eventually drift together and merge into a larger black hole some tens to hundreds of millions of years later.
Image credit: NASA/CXC/MIT/C.Canizares, M.Nowak
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