Solar storm

Time -   Solar storms can knock a wired planet sideways, disrupting communication and navigation satellites, power grids, defense systems, data centers, weather forecasting, and more. On Monday afternoon, the sun slugged the Earth with a massive flare, landing its most powerful energetic punch since the Great Halloween Storm of 2003. For the most part, we got off easy, with little infrastructure disruption reported. The biggest impact was actually a lovely impact: the northern lights, usually confined to the polar regions, have been visible across Canada, much of the U.S., and Europe.

... From the jump, the astronomers knew they had spotted a big one. Solar flares are divided into four categories according to their strength: B-class, C-class, M-class, and X-class, with B being the least powerful and X the most. As with earthquakes, the scale is logarithmic, so X is 10 times more powerful than M, which is 10 times more powerful than C, which is 10 times more powerful than B. This one was an X. It was headed our way and there was nothing to do but brace for the blow.

Earth has suffered worse. Within the M, C, B, and X categories is a more precise 1 to 9 scale, with 1 being the weakest and 9 the most powerful—so a B7, for example, will be stronger than a B3. The current storm is an X1.9. The Oct., 2003 flare was so powerful it blew out the detectors, exceeding the 1 to 9 scale and registering a whopping X17 before the instruments failed.