The storm could temporarily disrupt GPS signals and stress the North American power grid, according to Yihua Zheng, a scientist at NASA’s Space Weather Laboratory, but the Earth’s magnetic field will repel much of the radiation, protecting people on the ground.

The stormy space weather started with a potent sunspot that unleashed X-class solar flares — the strongest variety —on Sunday and again Tuesday evening.

“This was the sun’s version of Super Tuesday,” said Joe Kunches, a scientist at the Space Weather Prediction Center, part of the National Oceanic and Atmospheric Administration in Boulder, Colo.

This is what happens when a subset of a larger system gets too hot and energetic for the larger system to contain.  Also…lots of physics.
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Solar storms ramp up, take aim at Earth – The Washington Post
http://www.washingtonpost.com/national/health-science/solar-storms-ramp-up-take-aim-at-earth/2012/03/07/gIQAjodsxR_story.html