Solar Storm Nearly Sparked War in 1967

A solar storm jammed U.S. radars, which the Air Force took as a sign of an incoming attack.

When the United States and the Soviet Union were at the height of the Cold War, a solar storm could have been mistaken for an incoming attack, according to new research.

A solar storm on May 23, 1967 jammed U.S. polar surveillance radars, which the Air Force took as a sign of an incoming attack. However, space weather forecasters conveyed news of the storm -- and its potential to wreak havoc with communications -- just in time. Today it's better known that solar storms can cause electromagnetic disturbances that jam radio communications and power lines.

"This is a grave situation," lead author Delores Knipp, a space physicist a the University of Colorado in Boulder, said in a statement of the 1967 situation. "But here's where the story turns: things were going horribly wrong, and then something goes commendably right."

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At the dawn of the space age in the late 1950s, the U.S. military started watching solar activity to make better predictions about when space weather would affect Earth. This expanded into the Air Force's Air Weather Service (AWS) that looked for solar flares starting in the 1960s. Their observers were located around the country and spoke regularly with solar forecasters at the North American Aerospace Defense Command (NORAD), which controls and defends the airspace above North America.

Luckily for history, these reports were often sent daily to NORAD by 1967. On May 18 of that year, observers saw an unusually large group of sunspots in one spot on the sun. Five days later, the storm erupted and was visible to the naked eye in New Mexico and Colorado, according to observatories there. Because the flare was pointed approximately in the direction of the Earth, a coronal mass ejection of solar particles was expected to follow 36-48 hours later and hit our planet.

On the same day -- May 23 -- NORAD's Ballistic Missile Early Warning System's three radars in the north all jammed. A NORAD weather forecaster asked Arnold Synder, the on-duty solar forecaster that day, if the sun was being active at all. "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," said Snyder, who is now a retired colonel, in the same statement.

More evidence piled up for the sun's jamming, including the fact that the three BMEWS sites had the sun shining overhead at the time, and that the jamming lessened as solar activity faded. However, some unaware commanders put nuclear aircraft in "ready to launch" status during the jam.

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The authors of the study say NORAD's solar forecasting center sent information about the storm to these commanders, just in time. The Air Force ended up not launching the aircraft.

In future years, the military beefed up its space weather forecasting system to provide better information during solar storms. The 1967 storm disrupted U.S. radio communications for a week, but in a prettier side effect, northern auroras (which are caused by solar activity) were seen as far south as New Mexico.

A new paper on the event, based on interviews with retired U.S. Air Force officers, has been accepted for publication in Space Weather.