Throughout history, humanity has steadily increased its dependence upon technology. Although technology has vastly improved the quality of life for billions of people, it has also opened us up to new risks and vulnerabilities. Terrorism and natural disasters might be at the forefront of the minds of policymakers and the U.S. population, but a significant threat lurks over our heads: the sun. A massive solar storm, the size last seen a century and a half ago, could easily leave hundreds of millions of people in the dark for days, weeks or even months.