ARLA/CLUSTER: Faz 150 anos que houve a mega-storm

[Antonio Matias]

*GEOMAGNETIC MEGA-STORM: *On Sept. 2nd, a billion-ton coronal mass ejection
(CME) slammed into Earth's magnetic field. Campers in the Rocky Mountains
woke up in the middle of the night, thinking that the glow they saw was
sunrise. No, it was the Northern Lights. People in Cuba read their morning
paper by the red illumination of aurora borealis. Earth was peppered by
particles so energetic, they altered the chemistry of polar ice.

Hard to believe? It really happened--exactly 150 years ago. This map shows
where auroras were sighted in the early hours of Sept. 2, 1859:

<http://science.nasa.gov/headlines/y2008/06may_carringtonflare.htm>
*Above:* Aurora sightings, Sept. 2, 1859. Image courtesy J.L. Green, NASA

As the day unfolded, the gathering storm electrified telegraph lines,
shocking technicians and setting their telegraph papers on fire. The
"Victorian Internet" was knocked offline. Magnetometers around the world
recorded strong disturbances in the planetary magnetic field for more than a
week.

The cause of all this was an extraordinary solar
flare<http://science.nasa.gov/headlines/y2008/06may_carringtonflare.htm>
witnessed
the day before by British astronomer Richard Carrington. His sighting marked
the discovery of solar flares and foreshadowed a new field of study: space
weather. According to the National Academy of Sciences, if a similar flare
occurred today, it would cause $1 to 2 trillion in damage to society's
high-tech infrastructure and require four to ten years for complete
recovery.

A repeat of the Carrington Event seems unlikely from our low vantage in a
deep solar minimum--but don't let the quiet fool you. Strong flares can
occur even during weak solar cycles. Indeed, the Carrington flare itself
occured during a relatively weak cycle similar to the one expected to peak
in 2012-2013<http://science.nasa.gov/headlines/y2009/29may_noaaprediction.htm>.
Could it happen again? Let's hope
not<http://science.nasa.gov/headlines/y2009/21jan_severespaceweather.htm>
.
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