Geomagnetic storms create a magnetic charge of voltage and current, “essentially overloading” things like satellites and power grids, according to Mike Bettwy of the US Space Weather Prediction Center.
The most famous example came in 1859 during the worst solar storm in recorded history, called the Carrington Event.
As well as stunning auroras, the storm caused sparks to fly off of telegraph stations. The charge that originated from the Sun was so strong that some telegraphs worked without being plugged into a power source.
So what would happen if such a powerful geomagnetic storm struck Earth again?
Bettwy said most countries have improved their power grids, which should prevent prolonged outages like those that hit Sweden in 2003 or Canada in 1989.
Still, he suggested people have an emergency kit in case electricity is knocked out for a day or two. Fresh water might also help in case filtration plants go offline.
Astronauts are particularly at risk from radiation during extreme solar activity. Those on the International Space Station usually take the best shelter they can when a bad storm is expected.
Bettwy said a massive solar storm could expose astronauts to an “unhealthy dose” of radiation, but he did not think it would be lethal.
Emphasizing that he did not want to “instil fear,” Bettwy added that radiation can also potentially “get through the fuselage” of planes flying near the north pole.
Airlines sometimes change routes during extreme solar storms to avoid this happening, he added.
Several upcoming missions are expected to improve forecasting of the Sun’s intense and unpredictable weather, aiming to give Earth more time to prepare.
If the European Space Agency’s Vigil mission, planned to launch in 2031, was in place today, it would give us far more information about the currently rotating sunspot, ESA space weather service coordinator Alexi Glover said.