70TH ANNIVERSARY OF THE 1956 GROUND LEVEL EVENT
It doesn't have a catchy name, and most people have never heard of it. Yet space scientist Clive Dyer of the Surrey Space Centre can't stop worrying about 'GLE05'–a major solar radiation storm in 1956.
"Today is the 70th anniversary of that extreme space weather event," says Dyer. "If it happened again today, it would have a significant impact on air travel and modern technology."
[picrel: A drawing of the giant sunspot that caused the Feb. 23, 1956, GLE.]
On Feb. 23, 1956, radiation sensors around the world suddenly went haywire as radiation levels spiked to values as much as 50 times normal. No one had ever seen anything like it. "The increase was so dramatic that some observers switched-off their monitors believing them to be malfunctioning," says Dyer.
The radiation came from "McMath Region 3400"–an enormous sunspot spanning 60° in solar longitude, which flared just seconds before the particles arrived. Normally, our atmosphere would harmlessly absorb the radiation, but not this time. Solar particles penetrated all the way to the ground.
"We call this a Ground Level Enhancement (GLE)," explains Dyer, "This was the biggest of the modern era, and even today nothing has come close to matching it." (A widely publicized GLE last November only amounted to 2% of the 1956 event.)
According to Dyer's calculations, GLE05 would have delivered as much as 10 millisieverts of radiation to passengers on a high-altitude transatlantic flights–comparable to multiple chest CT scans in a few hours. The effect on satellites might have been significant except for one thing: There were no satellites. Sputnik wouldn't be launched until the next year.
How times have changed. in 2026, Earth is surrounded by a swarm of more than 10,000 active satellites with electronics so sensitive that even a single particle of "hard radiation" can reboot onboard computers or or burn out memory locations.
"Such energetic particle events are nearly impossible to shield," says Dyer. "We need to be prepared–not if but when this happens again."
Happy Anniversary!
https://spaceweather.com/archive.php?view=1&day=23&month=02&year=2026