Last week a dark spot on the Sun, nearly the size of Jupiter, let go with a massive solar eruption. For a number of days thereafter, scientists around the world waited to see if the discharged solar plasma and charged particles would interfere with communication systems, satellites, computer circuits and even the electrical grid. Fortunately, while northern parts of the globe witnessed a spectacular light show, communications systems and utilities went unscathed.Unfortunately, we may not always be so lucky. According to a study published last month by Space Weather: The International Journal of Research and Applications there is about a 12 percent chance that within the next decade such a solar storm hitting Earth could be powerful enough to significantly disrupt satellites and the power grid.So how prepared is the U.S. to take such an electromagnetic hit to its electric power distribution networks? To put it subtly: not so much. Experts say it could take months -- many months, to more than a year -- to power the grid back up should certain critical transformers be damaged in such an event. The implications to the population -- stricken without electrical power for such an extended period -- can't be overstated as access to medical care, food, fuel, and even running water is cut. The lack of preparedness isn't due to lack of understanding of the problem, explains Avi Schnurr, chairman and CEO of the Electronic Infrastructure Security EIS Council. "In terms of the legitimacy of EMP [Electromagnetic Pulse] as a concern, there's really no credible scientific opinion anywhere that would doubt it," says Schnurr. "The U.S. did a series of high-altitude nuclear tests starting in 1962. In fact, there was some surprise that the purely theoretical idea of EMP causing electrical issues happened so readily," says Schnurr. Schnurr explains how the first tests, known as Starfish Prime, caused electrical issues in Hawaii, more than 800 miles away from the upper atmosphere test explosion. A "natural EMP," such as that created by extreme space weather, could cause the same type of damage as a nuclear explosion high in the altitude. Experts explain that the threats of EMP events knocking out the power grid haven't increased, but rather our vulnerabilities to such events have, especially in recent decades. "We've steadily integrated more and more of our critical infrastructures into the electrical grid. We've got everything that our society depends on plugged into the grid, and the grid itself has now become vastly more sensitive to electromagnetic threats than ever before," says Schnurr. And, it turns out, since we've built the national power grid, mother nature has been unusually serene for us. "When researchers have gone back and conducted historical research to look at how bad space weather can get. What they found is that what we've experienced in modern time has actually been relatively benign relative to what has been experienced historically," Schnurr says. "The sun has not changed, but it was news to the energy sector that a bad day for the Sun can be a lot worse than we had realized," he said. To better prepare for the eventuality of severe space weather knocking out portions of the power grid, large transformers and other systems core to power delivery need to be hardened. So how much would it cost the U.S. to build some resiliency into the power grid? Dr. Peter Vincent Pry, former staff member of the congressional Commission to Assess the Threat to the United States from Electromagnetic Pulse Attack explained that several hundred of the big electrical transformers required to keep the electrical grid up and humming could be hardened at a cost of no more than $400 million. The federal government is moving, albeit slowly. In 2010, the House unanimously passed the Grid Reliability and Infrastructure Defense Act, which would amend the Federal Power Act to protect the bulk-power system and electric infrastructure critical. Similar Legislation is also moving along in the Senate. George V. Hulme writes about security and technology from his home in Minneapolis. You can also find him tweeting about those topics on Twitter @georgevhulme.