Answer: The Moon

During the Cold War, there were more than a few terrifying false alarms in both the U.S. and Soviet-run air defense systems. Among all the false alarms, one in particular had a rather enormous culprit: the Moon.

How could the Moon be mistaken for an onslaught of missiles headed toward North America? One of NORAD’s radar stations positioned on the far edge of Greenland had, in a truly bizarre fluke, caught a wave of interference from the Moon rising over Norway and the system had interpreted the huge signature as a swath of missiles coming from Russia (and automatically issued a high-certainty alert remotely to NORAD and Washington).

Although the false alarm generated by the Moon was quickly identified as false (it did seem odd, after all, that the Soviets would launch a massive nuclear strike on the U.S. when their leader was in New York City at the time meeting with the United Nations), the misstep of the system was pivotal in pushing the Air Force and NORAD to develop better systems that weren’t prone to confusing a lovely moonrise with a swarm of missiles.