A little more cautious than the Soviets, though, the British astronomers didn’t go public. They named the mysterious radio source LGM 1, for Little Green Men, and continued to study it. It turned out what they had was the first pulsar to be detected. A pulsar is the final state of a massive star that has collapsed down to about the size of New York City. As it rotates it can send out radio beams that seem, from our vantage here on Earth, to be turning on and off rapidly, like a code. But it’s an entirely natural phenomenon. Not that aliens sending out radio signals wouldn’t be a natural phenomenon as well. After all, there is one planet at least where indigenous life beams out radio signals all the time. You’re listening to one.