Earlier this year, my colleague Paul Seaburn wrote about the massive July 23, 2012 coronal mass ejection (CME) that almost collided with Earth. Solar physicists have examined the CME in more detail, and have determined that if the wave had happened a mere week earlier than it did, we would have been in for a mess:
"Analysts believe that a direct hit by an extreme CME such as the one that missed Earth in July 2012 could cause widespread power blackouts, disabling everything that plugs into a wall socket. Most people wouldn't even be able to flush their toilet because urban water supplies largely rely on electric pumps … According to a study by the National Academy of Sciences, the total economic impact could exceed $2 trillion or 20 times greater than the costs of a Hurricane Katrina. Multi-ton transformers damaged by such a storm might take years to repair."
Based on data collected by the Solar Terrestrial Relations Observatory (STEREO), the CME traveled at about 120,000 miles per hour and passed directly through Earth’s orbit—though it fortunately did about a week after Earth had passed that part of its orbit, and blasted harmlessly out into the outer solar system.
The plasma wave was huge, but the Earth is a relatively small object orbiting the Sun at a considerable distance, so any energy wave that collided with Earth would have to be pretty huge. How huge? Well, the Sun is about 865,000 miles in diameter, Earth is about 7,900 miles in diameter, and they’re about 93 million miles apart; imagine a grain of sand orbiting a tennis ball from 24 feet away, and you have the basic proportions right. So a coronal mass ejection that actually affects Earth would have to be pretty massive.
Unfortunately, the Sun spews out massive coronal mass ejections all the time; scientists estimate our odds of being clobbered with one are about 12% over the next ten years. So what happens when it does hit? Maybe nothing; maybe the nightmarish scenario described above; maybe anything in between. It all depends on the strength of the CME, the strength of the resulting geomagnetic storm, and a variety of factors we can’t quite assess yet. But if the data from the 2012 CME is any indication, Earth’s power grid isn’t ready for the consequences. Let’s hope we stay on the right side of that 12% figure—at least until we’ve had a chance to protect our infrastructure from the impact of solar storms.