ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun. Quasars are the most energetic and distant members of a class of objects called active galactic nuclei. Quasars are extremely luminous. Their spectra contain very broad emission lines, unlike any known from stars, hence the name "quasi-stellar". Their luminosity can be 100 times greater than that of the Milky Way.