The damage could total trillions of dollars and take months or years to fully mend.
It's a scenario every human on Earth could be facing had a massive solar storm not narrowly missed the planet two years ago.
"If it had hit, we would still be picking up the pieces," Daniel Baker of the University of Colorado told Tony Phillips of Science@NASA. "I have come away from our recent studies more convinced than ever that Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did. If the eruption had occurred only one week earlier, Earth would have been in the line of fire."
Baker and colleagues wrote a paper for the December 2013 issue of the journal Space Weather about the powerful storm formally called a coronal mass ejection (CME) that tore through the space between the Sun and Earth's orbit on July 23, 2012. A CME is composed of massive gas clouds that are threaded with magnetic field lines that wreak havoc on the planet's magnetic fields. Had it hit the Earth, there would not have been an impact crater, but the magnetic fields surrounding the planet would have been thrown into chaos.
Instead of hitting the planet, it struck NASA's STEREO-A (Solar Terrestrial Relations Observatory) spacecraft, which trails the Earth along the planet's orbit. The observatory was equipped to withstand CMEs and collect massive and detailed data about the effects of one.
The storm proved at least as powerful as the Carrington Event, which took place in September of 1859. Then, the Northern Lights stretched to Cuba and caused telegraph lines to spark and telegraph offices to start on fire.
The National Academy of Sciences said if the storm hit today, it would cause $2 trillion in damage. The multi-ton power transformers that would be fried could take years to mend.
"In my view the July 2012 storm was in all respects at least as strong as the 1859 Carrington event," says Baker. "The only difference is, it missed."
In a February 2014 paper in Space Weather, physicist Pete Riley of Predictive Science Inc. determined the likelihood of another, equally powerful storm occurring. The answer 12 percent in the next 10 years.
"Initially, I was quite surprised that the odds were so high, but the statistics appear to be correct," says Riley. "It is a sobering figure."
Further research on the megastorm showed that a small series of earlier storms cleared the path for the massive CME, according to findings by UC Berkeley space physicist Janet Luhmann and former postdoc Ying Liu.
"It's likely that the Carrington event was also associated with multiple eruptions, and this may turn out to be a key requirement for extreme events," Riley said. "In fact, it seems that extreme events may require an ideal combination of a number of key features to produce the 'perfect solar storm.'"
Scientists will continue to assess the data from the 2012 eruption, but if the 12 percent prediction holds true, the next data set might be when the next storm actually strikes the Earth.
"We need to be prepared," Baker said.