There are many important dates in history, a constant reminder of the best and worst pivotal moments humanity has to go through. But some days that didn’t make it into the history books are, sometimes, equally important.

May 23, 1967, is one such day. On that day, the United States surveillance radars in polar regions appeared to be jammed, the likely culprit being the Soviet Union preparing an attack. The cause for it was actually a powerful solar storm and military space weather forecasters provided the information just in time to avoid any hostilities between the two superpowers.

In a paper accepted for publication in Space Weather, a journal of the American Geophysical Union, space physicist Professor Dolores Knipp and retired members of the US Air Force discuss the geomagnetic storm and its potentially disastrous consequences for the first time. The research highlights the importance of space weather forecasting in both civil and military life.

“Had it not been for the fact that we had invested very early on in solar and geomagnetic storm observations and forecasting, the impact [of the storm] likely would have been much greater,” said Knipp in a statement.

“This was a lesson learned in how important it is to be prepared.”

The US military began to monitor solar activity and space weather in the later 1950s and by the 1960s, forecasting was a constant activity performed at the NORAD, the North American Aerospace Defense Command, a US and Canadian joint air defense effort.

On May 18, 2013, solar forecasters at NORAD noticed an increase in the number of solar spots. By May 23, observers and forecasters saw a ramping in radio emission from our star as well as a bright solar flare. Solar flares can generate powerful winds of charged particles that create geomagnetic storms, which can seriously interfere with electronics.

This caused the apparent jamming of radars. At the height of the Cold War, jamming radar was considered equivalent to a physical attack. The military commanders had to think that an attack was always imminent so during the solar storm, they put additional forces in a "ready to launch" status.

Retired Colonel Arnold L. Snyder, a solar forecaster at NORAD’s Solar Forecast Center, was on duty on that fateful day, and he was asked by the NORAD Command Post about any solar activity.

“I specifically recall responding with excitement, ‘Yes, half the sun has blown away,’ and then related the event details in a calmer, more quantitative way,” Snyder said.

Fortunately, Snyder’s report along with information from other observatories made it to the commanders in time. That Tuesday might have gone down in history in a very different way.