The Swedish civil aviation authority claims that a solar storm knocked out the air traffic control system in the country on Wednesday afternoon, and it was forced to close its airspace for over an hour.
According to the aviation officials, the solar storm created enough disturbance in the Earth’s magnetic field to stop the radar system working properly.
Per Froberg, the spokesperson for Luftfartsverket (the Swedish Civil Aviation Administration), told the Associated Press that flights disappeared from radar screens across Sweden. The radar blackout lasted for about an hour, but there is yet no explanation on why it was so severe.
"We're working on sorting out the delays. We can't examine the cause right now. We have our hands full," Mr Froberg added.
Neighboring countries such as Denmark and Finland didn’t report any problems in their ground instrumentation. "There haven't been any disturbances. Only a few delays in Copenhagen because of the problems in Stockholm," Mette Just of Naviair, Denmark's air navigation service, told the Associated Press.
And Juha-Pekka Luntama – head of the European Space Agency's Space Weather Coordination Centre – told IFLScience it was too early to blame a solar storm for the blackout.
“I think the event in Sweden yesterday was very interesting and we should wait for the technical analysis from the Swedish authorities before making any conclusions,” he said. “In my view the solar flare yesterday was not very strong and thus impacts in the air traffic control radar system in Sweden were unexpected.”
He continued: "Theoretically this kind of disturbance is possible, but these events are very rare and they would require a substantial radio burst from the Sun. Unexpected impacts may, of course, be possible when many inputs combine in the worst possible way. However, I would expect that other technical reasons will be identified as the main course for the radar problem. [Although] it is still possible that the solar flare was somehow one of the contributing factors.”
Solar storms happen when material from the Sun interacts strongly with the magnetic field of the Earth. The strongest interactions are due to shock waves in the solar wind (a stream of electrically charged particles constantly being emitted by the Sun), which are produced when eruptions from the solar surface are suddenly flung into space by freak magnetic events.
Solar storms can be very dangerous. One of the most intense solar storms in recent years was the Halloween Solar Storm of 2003, which caused an hour-long blackout in Sweden. The strongest solar storm on record, the Carrington event, happened in 1859. It was responsible for aurorae from the poles to the tropics as well as setting telegraph stations on fire across Europe and the United States. If it had happened today, it could produce trillions of dollars of damages in the U.S. alone.