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More than 150 years ago, the largest geomagnetic storm in recorded history occurred. Now we're in the midst of yet another solar maximum.
Richard Carrington and Richard Hodgson were out on a
normal September night in 1859 when they witnessed something extraordinary.
Although the two British astronomers were not working together, they were both
looking at the Sun via telescopes at the same time as a gigantic ejection
erupted from the blazing star. Others on Earth witnessed brilliant aurora
racing across the skies and telegraph cables bursting into sparks – the
advanced technology of the day in Europe and North America.
The solar flare was called after one of the two
scientists who initially described it, the Carrington Event. Despite the fact
that it occurred almost 150 years ago, it remains the strongest known
geomagnetic storm (though we lack measurements to say precisely how big it
was).
Since then, Earth has been hit by a few major
geomagnetic storms, all of which have resulted in power outages and satellite
damage. As a result, power companies and satellite manufacturers have made our
technology more resistant. What would happen, though, if a Carrington
Event-level solar flare occurred today? Were we prepared for it?
The answer, according to Alexa Halford, associate
chief of NASA's Goddard Space Flight Center's Heliophysics Science Division, is
a cautious yes. "We've got success," she says, "but there's still
a lot to learn."
Decades of learning:
Electromagnetic radiation explodes from the Sun,
causing flares. These surges usually last a few minutes, although they can
continue longer. Coronal mass ejections, which throw forth gas and magnetic
fields, are sometimes connected with them. However, not every solar flare or
coronal mass ejection will have an impact on Earth; the size and direction of
the burst are both factors. A solar flare that erupts on the Sun's far side,
for example, is unlikely to have any effect on us.
Even if it happens on the near side, the burst's
trajectory frequently misses us because we're so far away and such a little
target compared to the Sun. One of the greatest solar flares in recorded
history detonated into a coronal mass ejection in 2001, for example, with a
speed of around 4.5 million miles per hour. Fortunately, it passed us by on its
way into space.
The Carrington Event occurred in 1859, when technology
was very rudimentary, but it had a significant influence on telegraph lines.
People had to unplug the cables at the moment to prevent sparks from erupting.
However, thanks to the particles expelled from the flare that struck the
current in the lines, they remained somewhat functional. "They had to
unplug them," Halford adds, "but they still had enough energy and
currents to run for a while."
Of course, there have been previous solar flares that
have had an influence on Earth. A solar storm in 993 A.D. left evidence on tree
trunks that archaeologists are now using to date old wood materials, such as
the Viking settlement in the Americas. During World War I, another large solar
flare occurred. It wasn't as big as the Carrington Event, but it still threw
detecting systems into a loop. According to Halford, technicians thought bombs
were dropping when it was actually interference from the flare striking the
magnetosphere.
In March 1989, a huge coronal mass ejection hit Earth,
causing a geomagnetic storm that wreaked devastation on the planet. The flare
took off the electricity grids in Quebec and parts of New England for nine
hours, according to Hydro-Quebec. Due to an overabundance of electricity in the
grid, power transformers even melted.
Safety measures:
The 1989 event drew the attention of infrastructure
planners for the first time. "Those are the kinds of incidents from which
we've learnt a valuable lesson," Halford adds. To prevent cascading
failure, power companies began incorporating safety features such as tripwires
into the energy system. These tripwires are set to turn off if power climbs too
quickly, limiting damage and preventing transformer burnout, as happened in
1989.
Bit flips, surface charging, and internal charging of
satellites orbiting our globe can all be caused by geomagnetic storms, as
happened this October when a solar flare created a coronal mass ejection and a
geomagnetic storm that slammed Earth. Satellites are particularly vulnerable
because they do not benefit from our atmosphere's relative protection. However,
the majority of satellites launched in the last two decades have been designed
to withstand overcharging.
When ionised particles from solar outbursts switch the
function of memory bits, this is known as a bit flip. GPS satellites, which are
used for everything from navigation to precision drilling, might be severely
harmed as a result of this. Even banking relies on GPS satellites to determine
when transactions should take place. "That kind of failure would be
devastating to the economy," says Halford. "It's critical, and it's
something we should be concerned about."
While satellites are now more durable, she says that a
storm is unlikely to knock out enough GPS satellites to cause widespread
issues. These issues can sometimes be resolved by simply power cycling or
restarting the affected device. According to Halford, the October flare created
some minor challenges, but the Federal Aviation Administration did not disclose
any serious navigational issues.
It's also possible that another large solar flare will
occur around this time. It'll be a test of our safety procedures and
precautions, according to Halford, but don't hold your breath. According to a
2019 analysis, the likelihood of a Carrington-like event occurring before 2029
is less than 1.9 percent. "A Carrington Event is something you kind of
want to happen," Halford adds, "because we think we'll be able to
weather it."
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