As the world becomes more and more reliant on electronics, it’s worth a periodic reminder that a large solar flare could knock out much of the electronics on earth. Such an event would be devastating to the Internet, satellite broadband, and the many electronics we use in daily life.

A solar flare is the result of periodic ejections of matter from the sun into space. Scientists still aren’t entirely sure what causes solar flares, but they know that it’s somehow related to shifts in the sun’s magnetic field. The big balls of the sun’s matter discharge vast amounts of electromagnet energy in a wide range of particles and spectrum. Solar flares are somewhat directional, and the earth receives the largest amount of radiation when a flare is aimed in our direction.

A solar flare can happen at any time, but we know that peak solar flares are on an 11-year cycle, with the latest cycle started in December 2019. Scientists can see solar flares about eight minutes after they occur. The radiation from a flare hits the earth for the period between 17 and 36 hours after the flare.

Solar flares cause damage when the radiation from a flare pierces the protection afforded by the atmosphere. Small flares barely make it to earth and don’t cause much damage. But a large flare can pepper the earth’s surface with radiation that can spread stray signals through electrical wiring and cause damage to the components of the electric grid and any devices connected to it. Solar flares are particularly damaging to objects in space and can destroy electronics in satellites and even cause them to fall out of orbit.

The earth has been hit with big solar flares in the past. The biggest flare that we know about happened in 1859 and blew up telegraph equipment around the world. That solar flare pushed the aurora borealis as far south as Hawaii. In 2012 the earth missed a similarly large flare by only a week when the flare hit behind the earth’s orbit around the sun. A smaller flare in 1989 knocked out electricity in Quebec for nine hours. During Halloween week of 2003, there were a number of reported problems when 17 small solar flares erupted simultaneously. During that event, airplanes were rerouted, satellites were powered down, and the aurora borealis could be seen as far south as Florida.

The impacts of a big solar flare of the magnitude of the 1859 one would be devastating to electronics. NASA scientists estimated that a direct hit from the 2012 solar flare would have done over $2 trillion in damages to our electric grids.

Our reliance on electronics has skyrocketed since 2012. We now do a huge amount of our computing in the cloud. Our homes and businesses are full of electronic devices that could be damaged or ruined by a big solar flare. We communicate through hundreds of thousands of cellular sites. We are just in the process of delivering a lot of bandwidth from small satellites that could be destroyed or disabled by a big solar flare. Many routine daily events now rely on GPS satellites and weather satellites. We are moving manufacturing back to the US by the use of robotized and automated factories. An event that would have caused $2 trillion in damages in 2012 would likely cost a lot more today and even more damage in the future.

The purpose of this blog is not to cry wolf. But networks ought to have a plan if a giant flare is announced. The only good way to protect against a giant flare is to unplug electronics and remove devices from the grid—something that’s not easy to do in a modern network on less than 17 hours of notice. NASA estimates that the probability of a big flare this decade is around 12%, and that’s large enough to be worried about. But, inevitably, we’ll eventually get hit by one. Solar flares are a natural phenomenon, just like hurricanes. Still, unlike hurricanes, we increase the amount of theoretical damage from a big solar flare every time we make our life more reliant on electronics. But unlike hurricanes, we mitigate against the worst damage if we react quickly enough when a big flare is on the way.