Reid: Back in 1967, the world was very different. The Beatles were still together, people smoked and drank like they were on “Mad Men,” and NATO was locked in a simmering Cold War with Soviet Union and the rest of the Warsaw Pact.

In the middle of all this, a huge electromagnetic storm on the Sun disrupted the radar sensors meant to detect a nuclear missile launch against the United States. Understanding the science of what was going on was super important for everyone in the chain of command, because they only had a few minutes to make some very important decisions.

It all started with the Sun. Unlike the rock or gas that makes up the planets in our Solar System, the Sun is made of plasma, which is full of charged particles, and very, very hot. It’s the same stuff that makes up a lightning bolt, or the flame of a candle. On the surface of the Sun, called the photosphere, all these swirling electric charges create powerful magnetic fields.

And when energy from the magnetic fields builds up, it can be released in the form of powerful solar storms. These storms can hurl huge clouds of plasma, ions, and radiation into outer space in what’s known as a coronal mass ejection. These storms happen on the Sun all the time.

When the radiation gets close to us, it gets pulled toward the north and south poles by the Earth’s magnetic field. Air molecules in the upper atmosphere absorb the energy from charged particles in the plasma, and start glowing. That’s what’s happening when you see the Northern and Southern Lights, or the Aurora Borealis and Aurora Australis, respectively.

Usually, that’s all that happens. But if the Sun has a really powerful storm, and Earth gets hit with much more plasma and electromagnetic radiation than usual, the air molecules in the upper atmosphere can’t absorb all that energy. Some of it gets down to the surface.

And that’s exactly what happened in 1967. On May 18th, 1967, the U.S. Air Force Air Weather Service saw a large group of sunspots, which are slightly cooler, highly magnetized regions of the photosphere. Sunspots are one of the first signs that a solar storm is brewing — and this looked like it was going to be a big one.

On May 23rd, they saw the Sun erupt in one of the largest bursts of radio waves ever recorded. But not only that, these radio waves had a very specific frequency: 440 megahertz.

See, back in the 1960s, the U.S. and its allies had a line of radar stations in Alaska, Greenland, and the U.K. to watch for Soviet nuclear missiles flying over the arctic. It was called the Ballistic Missile Early Warning System, or BMEWS. If the system detected anything, the U.S. would have about fifteen minutes to launch a nuclear counter attack before the missiles hit.

The BMEWS radar stations worked by sending a beam of radio waves into the sky. If the beam hit a missile, it would bounce back to the station and be detected. These radar stations used radio waves with a frequency of 440 megahertz, the same frequency as the radio waves coming from the Sun on May 23rd. The North American Air Defense Command, or NORAD, which monitored the BMEWS stations, suddenly saw that the stations were picking up some weird signals. The radio waves from the Sun had completely overwhelmed the detectors at the BMEWS stations.

To NORAD, it looked as though the stations were being jammed. If this were true, it was an act of war. It meant Soviet missiles might already be on their way. The U. S. Air Force had trained for this scenario. Aircrews would immediately prepare their planes for takeoff, carrying nuclear weapons to retaliate.

Now, there weren’t actually missiles headed for the US. But the Air Force thought there were, and if they’d launched missiles in response, then the Soviet Union would have launched its nuclear weapons for real, setting off a global nuclear catastrophe.

Luckily, solar forecasters at NORAD were able to combine the readings from the BMEWS stations and the information from the Air Weather Service. They predicted — correctly — that there was no Soviet attack, and that the jamming would clear up in just a few minutes.

The Air Force waited those few minutes, saw that the signal cleared, and no planes took off. The crisis was averted. So it pays to understand the science of outer space. You never know when humanity’s survival might depend on it.

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