Supermassive black hole, illustration. This black hole is located in the ultra-dense galaxy M60-UCD1 in the constellation of Virgo, 50 million light years from Earth. M60-UCD1 (140 million stars in a diameter of 300 light years) is the smallest known galaxy to contain a supermassive black hole. This black hole, with a mass of 21 million Suns, was detected by combined observations by the Hubble Space Telescope and the Gemini North telescope. This observation suggests dwarf galaxies are the remnants of larger galaxies that were torn apart, rather than galaxies formed in isolation. Image published in 2017.