While you might assume that black holes are, well, black, there is a small class of black holes that are oxymoronically bright. Named because they were originally mistaken for distant stars, these quasi-stellar objects, or quasars, are supermassive black holes at the centers of galaxies in the early universe that are actively and violently devouring gas. This accretion process produces large amounts of radiation that astronomers can observe and measure, providing insights into the environment...
