Solar storms are both fascinating and frightening. They're a natural phenomenon that we can't control and they have the potential to wipe out many of the gains of modern civilization. But what are they?
I covered some of the science in my own novel, Solar Storm, but basically it's what happens when the sun belches out a magnetically charged glob of plasma into space. Why does the sun do this? Because it's a highly energetic fusion reactor filled with clashing magnetic fields that occasionally react with each other to eject plasma into space.
Throwing stuff into space is something the sun does on a regular basis. We actually get hit by charged particles from the sun quite a lot. It's what causes the phenomenon that we call northern (or southern) lights, or aurorae. Charged particles interact at the poles with the magnetosphere that surrounds and protects earth, giving us beautiful colors. Sometimes a large encounter of such particles can affect astronauts and even passengers on planes flying at high altitudes, which is why these things are monitored to reduce exposure, but down on earth we merely take pictures if we're lucky enough to ever see an aurora.
Generally speaking (and I'm trying to keep things uber-simple here), that's the low level stuff that the sun throws at us. Occasionally we get the big stuff, known as a Coronal Mass Ejection, and you can liken it to a blob of lava sent into space. This stuff varies in size but is always highly charged, and if it happens to hit the earth as we orbit the sun, interesting things occur.
Bored of the science yet? Let's jump straight to the event that put Solar Storms on the map: The 1859 Carrington Event.
One day an English astronomer named Richard Carrington noticed a cluster of dark spots on the sun. The next day he read about the most bizarre incidents occurring in the US and concluded they were connected, duly filing a report with the Royal Astronomical Society. That was the day the science of solar storms began.
In the USA, newspapers wrote of night skies bright with weird colors, so bright in fact that miners assumed it was the dawn and began making their breakfast before their shift. Huge surges of electricity through telegraph wires melted platinum electrodes, gave electric shocks to telegraph operators and caused sparks that set printer paper on fire. For the whole of the next day, long after the storm, electricity continued to surge through the wires, allowing the operators to disconnect the batteries and continue sending messages down the still-electrified wires.
The telegraph was a new thing then, which is what gave everyone their first clues as to the power of such events. The same thing could have happened a million times before without anyone really noticing much. So how did the solar storm create electricity in the wires?
If you fold a piece of wire and rotate it between two powerful magnets, a current will be induced in the wire. This is how electricity generators work. The impact of the charged plasma on the earth's magnetosphere turned our atmosphere into a giant generator.
The interesting thing is that both the incoming plasma and our magnetosphere contain negative-positive polarities, just like a magnet. This is why we can get compasses to point to the north pole rather than south. If the earth's polarity shifts (as it will do one day), the compass needle will flip the other way. Now, if the polarity of the arriving plasma aligns with that of the earth, it will have zero effect. It can be the biggest mass ejection ever recorded, but it will just slide over us and do nothing. If the plasma is opposite aligned, however, the resulting electromagnetic pulse (EMP) on earth could be catastrophic.
Now, here's the thing. The Carrington Event is the largest geomagnetic storm ever recorded. But in actual fact, it wasn't really recorded. All we have are observations and anecdotes. The scientific instruments to record data about the event hadn't been invented or built yet.
We don't know what the relative polarity of the Carrington Coronal Mass Ejection was. We don't even know how big the ejected plasma cloud was, nor how long it was in contact with the earth's magnetosphere for. We only have educated guesses.
We have no idea if that was the most that our sun was capable of.
And that's the scary thing. Our modern world has a lot more than telegraph wires now. We have wires going everywhere and in everything. We have sensitive electronics that need to be protected from even the smallest of surges. We have wire fences (yes, fences induce electricity too) and aerials and wiring looms. And we rely on all of it.
We cannot predict the sun's activities yet, we can only record the polarity of a coronal ejection when it's about an hour from hitting us and we don't know how big the 'big one' will be. But we will do one day. That's when we'll learn how vulnerable our civilization is.