Watch on Soap2day. How can scientists study a faraway black hole that emits no light? By observing its quasar. As objects get pulled onto the accretion disk orbiting a supermassive black hole, friction creates a bright light known as a quasar. In this video, researchers use a “galaxy-sized lens” to analyze light from a distant quasar—revealing a supermassive black hole with a truly voracious appetite.