Solar storm of 1859
From Wikipedia, the free encyclopedia
(May 2011)
Sunspots of September 1, 1859 as sketched by Richard Carrington A and B mark the initial positions of an intensely bright event, which moved over the course of 5 minutes to C and D before disappearing.

The solar storm of 1859, also known as the Solar Superstorm,[1] or the Carrington Event,[2] which occurred during solar cycle 10, was the most powerful solar storm in recorded history, and the largest flare, observed by Richard Christopher Carrington, became known as the Carrington Super Flare.

[link to en.wikipedia.org]

***************************************************


[link to science.nasa.gov]

excerpt:

Right: Power transformers damaged by the March 13, 1989, geomagnetic storm: more.

Another Carrington-class flare would dwarf these events. Fortunately, says Hathaway, they appear to be rare:

"In the 160-year record of geomagnetic storms, the Carrington event is the biggest." It's possible to delve back even farther in time by examining arctic ice. "Energetic particles leave a record in nitrates in ice cores," he explains. "Here again the Carrington event sticks out as the biggest in 500 years and nearly twice as big as the runner-up."

These statistics suggest that Carrington flares are once in a half-millennium events. The statistics are far from solid, however, and Hathaway cautions that we don't understand flares well enough to rule out a repeat in our lifetime.