In the 1960s astronomers developed telescopes capable of detecting radiowaves (electromagnetic radiation like visible light, but with much longerwavelengths). Surprisingly, they detected several sources which were bright in radio waves, but looked like very faint stars at visible wavelengths. These starlike objects were called quasi-stellar radio sources - “quasars”. Further observations of the spectra of quasars at visible wavelengths showed that they were, in fact, not stars, but galaxies with extremely large redshifts, meaning that they were very distant. Quasars are now known to be galaxies with a central supermassive black hole – a black hole ranging in mass from millions to billions of times the mass of our sun. A quasar’s remarkable output of energy comes from material that is about to be consumed by the black hole. Quasars are amongst the most luminous objects in the known Universe - typically thousands of times more powerful than the entire Milky Way Galaxy. Dr. Martin Duncan
