A faint blue star in your backyard telescope might actually be a supermassive black hole shining four trillion times brighter than the sun from billions of light years away. This episode tells the detective story of quasars, from the anomalous radio sources of the 1950s to John Bolton and Cyril Hazard's lunar occultation of 3C 273 and Maarten Schmidt's realization that its alien-looking spectrum was ordinary hydrogen redshifted by 15.8 percent.

We explain why gravitational redshift from a nearby dense star was ruled out by the Hayashi limit and forbidden spectral lines, how flickering proved quasars are smaller than our solar system, and why the 1960s energy crisis spawned theories of white holes, wormholes, and antimatter before Salpeter and Zeldovich proposed accretion onto supermassive black holes. The episode covers accretion disk frict ...