It was five years ago when the Sun decided to show us who's boss.
It was well past the solar max, the time when the twisted magnetic field of the Sun is at its worst. Things were dying down. In general, the biggest and most powerful explosions of released magnetic energy do lag the actual solar max by about a year, but we were well past that.
No one expected that in October and November of 2003 the Sun would unleash the most violent flares ever seen in modern times. One was so huge it was reclassified more than once, upgraded to be the nastiest event ever detected. The Sun, it seemed, can still surprise us.
NASA has put together some information on the fifth anniversary of this event. They also put together a video (it was for Halloween, hence the ghouliness).
I wrote about this extensively in my book. I learned a huge amount about the properties of the Sun, and what sort of damage it can do on Earth. It's funny: to the eye you'd never see a flare; the Sun doesn't get much brighter overall, so you'd hardly notice. But it can blow out transformers, melt power lines, and cause billions -- yes, billions -- of dollars in damage. We're at the minimum of the solar cycle right now, but things are starting up again. Things will peak in about 5-6 years. What will happen two years after that?
Tip o' the transformer to Rani Gran at the NASA/Goddard Space Flight Center Public Affairs Office!