Yuri's Night: Supermassive Black Holes

Most galaxies have a supermassive black hole with a million to a billion times the mass of the sun at their center. Even our own Milky Way hosts such a monster, and when they start feeding on gas and dust, they start shining so bright that they put out more energy than a hundred billion stars in a galaxy put together. What role do these quasars have in shaping the growth of galaxies? How do astronomers study these objects and how can citizen scientists help us understand them?