Finally, he reported to his superiors: This was a false alert. The decision stopped imminent Soviet retaliation on the night of 27 September 1983, a date which might just have marked the end of modern civilisation. Later enquiries demonstrated the Oyo satellites had been misled by an unusual combination of sunlight bouncing off of high-altitude clouds and the satellites’ unusual highly-elliptical Molniya orbits. To Colonel Petrov, the evidence of his eyes didn’t seem right: “I had a funny feeling in my gut,” he later said in an interview . In training, Petrov had been taught the United States would seem...