Oww!

I bet this one hurt:

Caption: On Valentine's Day (ET) the Sun unleashed one of its most powerful explosions, an X-class flare.

The blast was the largest so far in the new solar cycle.

Erupting from active region AR1158 in the Sun's southern hemisphere, the flare is captured here in this extreme ultraviolet image from the Solar Dynamics Observatory (SDO).

The intense burst of electromagnetic radiation momentarily overwhelmed pixels in SDO's detectors causing the bright vertical blemish.

This X-class flare was also accompanied by a coronal mass ejection (CME), a massive cloud of charged particles traveling outward at nearly 900 kilometers
per second.

APOD: 2011 February 17: X-Class Flare

Here's what that link had to say about X-class flares:

X-class flares are big; they are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms.

The Classification of X-ray Solar Flares

Having the Solar Dynamics Observatory looking at the Sun gives us at least a few minutes' warning before all that hits the Earth. That gives electric utilities, communications providers, and computer installations a few minutes to make preparations, at least. Wikipedia says that it takes light, which travels at 300,000 kilometers per second, about eight minutes to reach the Earth from the Sun, and if you just divide 150 million kilometers by 300,000 kilometers per second, that works out about right. It's not a lot of time, but if there are procedures in place already, then at least some measures can be taken.

Which is yet another benefit of having a real space program.

Afterword: By the way, I found this in a round-about way, by visiting the NASA Satellites blog.