Near Miss: The Solar Superstorm of July 2012
In short: a coronal mass ejection shot out of the sun and came near-ish to the Earth. It was at least as powerful as the CME that hit the Earth in 1859, the so-called “Carrington Event” (named after the astronomer who linked a solar flare and the geomagnetic storm that followed). This event had some interesting effects:
1) Aurora visible as far south as Cuba and Hawaii
2) In the northeast, aurora so bright you could read by them at night
3) Telegraph offices burst into flames due to the induced currents
4) Telegraph systems that functioned *without* being powered up due to the induced currents.
Had the July 2012 CME hit the Earth, we could have expected some or all of the following:
1) A whole lot of fried satellites: say goodby to satellite TV, intercontinental communications, weather satellites, GPS
2) Phone land-lines would have been charged up, perhaps setting your phones/modems on fire (and perhaps the rest of your house)
3) Power lines would have been charged up, blowing up a *lot* of transformers and shutting down large power grids
It would have been basically a giant EMP attack. Things like your laptop, your cell phone, your car even a house with its own diesel/PV/wind generators would have been fine, since the length of the conductors involved are likely far too short to build up enough current to cause trouble. But for conductors *miles* long, like phone and power lines, you could expect to see massive damage. Lights out, basically. And getting the lights back on would be a hell of a challenge.
Chances of another such solar superstorm hitting the Earth in the next decade; 12%.