The Great Storm: Solar Tempest of 1859 Revealed

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A pair of strong
solar storms that hit Earth late last week were squalls compared
to the torrent of electrons that rained down in the "perfect
space storm" of 1859. And sooner or later, experts warn, the
Sun will again conspire to send earthlings a truly destructive bout
of space weather.

If it happens
anytime soon, we won’t know exactly what to expect until it’s over,
and by then some modern communication systems could be like beachfront
houses after a hurricane.

In early September
in 1859, telegraph wires suddenly shorted out in the United States
and Europe, igniting widespread fires. Colorful aurora, normally
visible only in polar regions, were seen as far south as Rome and

The event 144
years ago was three times more powerful than the strongest space
storm in modern memory, one that cut power to an entire Canadian
province in 1989. A new account of the 1859 event, from research
led by Bruce Tsurutani of NASA’s Jet Propulsion Laboratory, details
the most powerful onslaught of solar energy in recorded history.

Solar conspiracy

Space storms
are created when the Sun erupts, sending charged particles racing
outward, an expanding bubble of hot gas called plasma.

In 1859, four
crucial events conspired at one moment, Tsurutani told

"The plasma
blob that was ejected from the Sun hit the Earth," he said.
That’s a relatively routine event. What preceded the strike was
more unusual. "The blob came at exceptionally high speeds.
It took only 17 hours and 40 minutes to go from the Sun to Earth."
Solar storms typically take two to four days to traverse the 93
million miles (150 million kilometers).

"The magnetic
fields in the blob, called a coronal mass ejection, were exceptionally
intense," Tsurutani said. "And the fourth, most important,
ingredient was that the magnetic fields of the blob were opposite
in direction from the Earth’s fields."

Earth’s magnetic
field normally protects the surface of the planet from a continual
flow of charged particles, called the solar wind, and even does
a pretty good job defending against some storms. When a storm swept
past Earth last Friday, it met up with magnetic field pointed in
such a way that it thwarted the storm’s effects. That’s not always
the case.

In 1859, the
planet’s defenses were overwhelmed.

That was

Society back
then did not notice the storm the way it would today. The telegraph
was 15 years old. There were no satellite TV feeds, no automated
teller machines relying on orbiting relay stations, and no power

Tsurutani said
scientists can’t yet accurately measure or predict what the strength
or direction of Earth’s magnetic field will be when a storm arrives.
The storms themselves can be predicted. And Tsurutani says there
will eventually be another one like 1859.

"It could
very well be even more intense than what transpired in 1859,"
he says. "As for when, we simply do not know."

the rest of the article

17, 2010

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