A mysterious event detected by U.S. satellites in 1979 was the detonation of an atomic bomb. The incident correlates with an equally mysterious rise in radioactivity in sheep in nearby Australia, confirming that a nuclear test took place. Experts believe that Israel and South Africa conducted a secret joint test of a tactical nuclear weapon in the Indian Ocean, hoping it would escape detection. On September 22, 1979, a U.S. Vela satellite, part of the globe-scanning U.S. Nuclear Detonation Detection System (NDS), detected the characteristic “double flash” of a nuclear weapon. Nuclear bombs produce two distinct flashes: the superheating of...