Last time we mentioned the time when Soviet radio astronomers went public with the most amazing find ever — they were listening in on radio signals from an alien civilization. As it turned out, what they were actually listening to was a quasar: the blazing core of a galaxy that can emit radio waves that fluctuate in a regular pattern. So regular, in fact, that people thought it was an alien intelligence. Well, it wasn’t. But then, in nineteen sixty-seven, British radio astronomers spotted a signal much closer to our planet that was turning on and off with unbelievable regularity. Sure, the Soviets had been duped by the same kind of thing, but the exactitude with which this signal kept time was astounding — it was accurate to ten figures! It had to be a beacon of some kind. Aliens!