A dwarf galaxy 500 times smaller than our own Milky Way has a giant dark heart, scientists have discovered.
M60-UCD1 is the smallest galaxy known to contain a super-massive black hole at its centre, one with a mass equivalent to 21 million suns. The finding suggests that huge black holes may be more common than was previously thought.
A black hole is a region where matter has become so densely squeezed that not even light can escape its gravitational pull.