Repeat of 1859 Carrington Event would devastate modern world, experts say.
On February 14 (2011) the sun erupted with the largest solar flare seen in four years—big enough to interfere with radio communications and GPS signals for airplanes on long-distance flights.
As solar storms go, the Valentine's Day flare was actually modest.
But the burst of activity is only the start of the upcoming solar
maximum, due to peak in the next couple of years.
"The sun has an activity cycle, much like hurricane season," Tom Bogdan,
director of the Space Weather Prediction Center in Boulder, Colorado,
said earlier this month at a meeting of the American Association for the
Advancement of Science in Washington, D.C.
"It's been hibernating for four or five years, not doing much of
anything." Now the sun is waking up, and even though the upcoming solar
maximum may see a record low in the overall amount of activity, the
individual events could be very powerful.
In fact, the biggest solar storm on record happened in 1859, during a
solar maximum about the same size as the one we're entering, according
That storm has been dubbed the Carrington Event, after British
astronomer Richard Carrington, who witnessed the megaflare and was the
first to realize the link between activity on the sun and geomagnetic
disturbances on Earth.
During the Carrington Event, northern lights were reported as far
south as Cuba and Honolulu, while southern lights were seen as far north
as Santiago, Chile. (See pictures of auroras generated by the Valentine's Day solar flare.)
The flares were so powerful that "people in the northeastern U.S.
could read newspaper print just from the light of the aurora," Daniel
Baker, of the University of Colorado's Laboratory for Atmospheric and Space Physics, said at a geophysics meeting last December.
In addition, the geomagnetic disturbances were strong enough that
U.S. telegraph operators reported sparks leaping from their
equipment—some bad enough to set fires, said Ed Cliver, a space
physicist at the U.S. Air Force Research Laboratory in Bedford, Massachusetts.
In 1859, such reports were mostly curiosities. But if something
similar happened today, the world's high-tech infrastructure could grind
to a halt.
"What's at stake," the Space Weather Prediction Center's Bogdan said,
"are the advanced technologies that underlie virtually every aspect of
Solar Flare Would Rupture Earth's "Cyber Cocoon"
To begin with, the University of Colorado's Baker said, electrical
disturbances as strong as those that took down telegraph machines—"the
Internet of the era"—would be far more disruptive. (See "The Sun—Living With a Stormy Star" in National Geographic magazine.)
Solar storms aimed at Earth come in three stages, not all of which occur in any given storm.
First, high-energy sunlight, mostly x-rays and ultraviolet light,
ionizes Earth's upper atmosphere, interfering with radio communications.
Next comes a radiation storm, potentially dangerous to unprotected
Finally comes a coronal mass ejection, or CME, a slower moving cloud
of charged particles that can take several days to reach Earth's
atmosphere. When a CME hits, the solar particles can interact with
Earth's magnetic field to produce powerful electromagnetic fluctuations.
(Related: "Magnetic-Shield Cracks Found; Big Solar Storms Expected.")
"We live in a cyber cocoon enveloping the Earth," Baker said. "Imagine what the consequences might be."
Of particular concern are disruptions to global positioning systems
(GPS), which have become ubiquitous in cell phones, airplanes, and
automobiles, Baker said. A $13 billion business in 2003, the GPS
industry is predicted to grow to nearly $1 trillion by 2017.
In addition, Baker said, satellite communications—also essential to many daily activities—would be at risk from solar storms.
"Every time you purchase a gallon of gas with your credit card, that's a satellite transaction," he said.
But the big fear is what might happen to the electrical grid, since
power surges caused by solar particles could blow out giant
transformers. Such transformers can take a long time to replace,
especially if hundreds are destroyed at once, said Baker, who is a
co-author of a National Research Council report on solar-storm risks.
The U.S. Air Force Research Laboratory's Cliver agrees: "They don't have a lot of these on the shelf," he said.
The eastern half of the U.S. is particularly vulnerable, because the
power infrastructure is highly interconnected, so failures could easily
cascade like chains of dominoes.
"Imagine large cities without power for a week, a month, or a year,"
Baker said. "The losses could be $1 to $2 trillion, and the effects
could be felt for years."
Even if the latest solar maximum doesn't bring a Carrington-level
event, smaller storms have been known to affect power and
The "Halloween storms" of 2003, for instance, interfered with
satellite communications, produced a brief power outage in Sweden, and
lighted up the skies with ghostly auroras as far south as Florida and
Buffing Up Space-Weather Predictions
One solution is to rebuild the aging power grid to be less vulnerable to solar disruptions.
Another is better forecasting. Scientists using the new Solar
Dynamics Observatory spacecraft are hoping to get a better understanding
of how the sun behaves as it moves deeper into its next maximum and
begins generating bigger storms. (See some of SDO's first sun pictures.)
These studies may help scientists predict when and where solar flares
might appear and whether a given storm is pointed at Earth.
"Improved predictions will provide more accurate forecasts, so
[officials] can take mitigating actions," said Rodney Viereck, a
physicist at the Space Weather Prediction Center.
Even now, the center's Bogdan said, the most damaging emissions from
big storms travel slowly enough to be detected by sun-watching
satellites well before the particles strike Earth. "That gives us
[about] 20 hours to determine what actions we need to take," Viereck
In a pinch, power companies could protect valuable transformers by
taking them offline before the storm strikes. That would produce local
blackouts, but they wouldn't last for long.
"The good news is that these storms tend to pass after a couple of hours," Bogdan added.
Meanwhile, scientists are scrambling to learn everything they can
about the sun in an effort to produce even longer-range forecasts.
According to Vierick,
space-weather predictions have some catching up to do: "We're back where
weather forecasters were 50 years ago."