The M60-UCD1 is a dwarf galaxy that's so dense, you'd see 1 million stars at night if you lived in it instead of the 4,000 we typically see on Earth. Now, thanks to data from Hubble, NASA found that the galaxy, which is only 1/500th the diameter of Milky Way, has a humongous black hole that takes up 15 percent of its mass. Compared to the black hole in our galaxy, which has a mass of 4 million suns, M60-UCD1's has the mass of 21 million suns. Just take a look at the artist rendering above to see how a huge black hole would look amidst a super dense collection of stars. NASA, by the way, describes black holes as "a great amount of matter packed into a very small area" with "a gravitational field so strong that nothing, not even light, can escape."