If there’s a possibility worse than a full-scale exchange of nuclear weapons, maybe it’s a full-scale exchange of nuclear weapons launched because of a simple misunderstanding. In 1967, we may come close to that scenario, but you can thank some meteorologists for the fact that it didn’t come to pass.

In late May of 1967, an active spot on the Sun threw a remarkable storm our way, and it continued over several days. The spot released charged particles and serious bursts of radiation in the radio portion of the electromagnetic spectrum (among other things), disturbing the Earth’s ionosphere and magnetic field. All this resulted in disruptions to radio communications and radar systems for a few days—as well as Northern Lights seen as far south as New Mexico.

Critically, the early disruptions included NORAD’s newly built Ballistic Missile Early Warning System. The three high-latitude radar stations (in Alaska, Greenland, and the UK) pretty much went dark in the afternoon of May 23. As the Sun sank lower in the sky, these radar systems were pointed right at the source of the radio emissions just as they arrived. To US military leaders, it seemed an awful lot like jamming—Russia blinding the eyes watching for incoming nuclear weapons. Did that mean there were missiles or aircraft en route?