This photo from NASA captures a solar
eruption in action. See more sunspot pictures.
NASA Glenn Research Center
(NASA-GRC)
A song written by Hy Zaret and Lou Singer, later
popularized by the band They Might Be Giants, claims that
"the sun is a mass of incandescent gas, a gigantic nuclear
furnace." Upon closer examination, it appears that this
initial classification of the sun is a little too narrow. It
turns out that the sun is a complex body that we still don't
understand fully.
But here's what we do know: The sun is a massive object
comprised of intensely hot, ionized gases. We call this kind
of gas plasma and it's the most common
state of matter in the universe. The atoms that make up the
gases in the sun are so hot that they can't hold on to their
electrons. The gases flow in currents through the sun,
carrying electrons with them.
If you're familiar with
electromagnets, you know that an
electrical current can create a
magnetic field. That's the case with the sun. The sun
has an enormous magnetic field around it. The rotation of
the sun perpetuates this magnetic field.
To make matters more complicated, hot objects tend to
expand. The sun is an extremely hot object. But the sun is
also large and dense, which means it has a strong
gravitational pull. The sun's gravity balances out its
tendency to expand.
The combination of these forces can cause the sun's
surface to change in dramatic and sometimes violent ways.
The currents of gas cause magnetic field lines to twist.
That can prevent hotter gases from the sun's core from
rising to the surface, creating sunspots.
Sunspots appear darker than the rest of the sun's surface.
They are also cooler than the brighter areas that surround
them.
The hot gas trapped beneath sunspots exerts pressure on
the magnetic field lines that prevents the gas from reaching
the surface. This winds the magnetic field lines into
tighter coils. Sometimes, even more field lines become
entangled. Once in a while, the magnetic field lines will
uncoil without much incident and the sunspot fades as the
hot gases rise to the surface. But sometimes the pressure
continues to build until the magnetic field lines snap out
suddenly, causing a solar flare.
Solar Flares and Coronal
Mass Ejections
A solar flare isn't just an explosion of hot gases.
It pushes out waves of light all across the spectrum.
That includes
light we can't see -- including radiation in the
form of
X-rays and gamma rays. These rays can be dangerous
to humans. Fortunately, the
Earth's atmosphere absorbs most of these high-energy
rays.
That's not to say everyone is in the clear after a
solar flare. Humans in space or at high altitudes -- on
board an
airplane, for example -- could risk exposure to
intense radiation. Short-term damage could include skin
irritation. Long-term consequences might include an
increased risk of developing skin
cancer. But it's likely that any affected human
would eventually recover from the exposure.
Electronics are also vulnerable to these rays. If
high-energy rays were to hit a
satellite, they could strip electrons from the metal
components, ionizing them. As electrons break free, they
could short out the electronics within a satellite. They
could also create a magnetic field that would damage the
satellite's systems. Some satellites have shielding to
protect them from these rays, but many are still
vulnerable.
Because our atmosphere absorbs most of these
dangerous rays, terrestrial systems are fairly safe from
solar flares. But another solar event called a
coronal mass ejection (CME) can cause serious
problems for electrical systems here on Earth. During a
CME, the fluctuations of the
sun's magnetic fields cause a large portion of the
surface of the sun to expand rapidly, ejecting billions
of tons of particles out into space. Sometimes CMEs
accompany solar flares -- but not all solar flares
produce CMEs and not all CMEs accompany solar flares.
Unlike a solar flare, a CME doesn't produce intense
light. But it does produce a magnetic shockwave that
extends billions of miles out into space. If
Earth is in the path of that shockwave, our planet's
magnetic field will react to the event. It's similar to
what happens if you put a weak magnet next to a strong
one. The weak magnet's field will align itself to the
strong magnet's field. A magnetic shockwave from the sun
could cause the alignment of the Earth's magnetic field
to shift unpredictably.
Pretty lights aren't the only consequence from a CME.
The magnetic fluctuations can cause compasses to fail.
And since magnetic fields can induce
electricity, any conductor could become an inductor.
A powerful CME could induce electricity in large,
powerful conductors. That could overload electrical
systems and cause massive damage.
Next, we'll take a look at exactly how badly off we
could be after a massive CME event.
Frying Electronics with the
Sun
While a solar flare alone might not be enough to
cause problems on
Earth's surface, a powerful CME is another story. In
fact, massive CMEs have affected the Earth in the past.
But we weren't as advanced in electronics, nor did we
depend upon them as heavily the last time a CME really
smacked us around.
In 1859, an enormous CME caused massive magnetic
fluctuations in the Earth's magnetosphere
-- the
magnetic field surrounding the planet. People living
as far south as Cuba witnessed the northern lights
phenomenon. Compasses and telegraph systems failed.
Scientists and academics debated the cause of all the
commotion. We now know it was due to a CME. The CME was
so massive that it caused what we call a solar
superstorm.
Today, we depend much more heavily upon electronics
and electricity than we did in 1859. If a similar solar
superstorm were to hit us now, we'd be in trouble. The
magnetic forces would induce
electricity in any large conductor. That includes
power transformers and the power grid itself.
That's not the end of the bad news. The power grid in
North America operates at near capacity. It wouldn't be
able to handle the increased electrical load from a
solar superstorm. Power lines could sag and even snap as
a result. Massive power outages could affect much of the
continent. The magnetic fluctuations would interfere
with
radio signals, and communication and
satellite systems would collapse as well.
It could take weeks or months to repair the damage.
During that time, people would have no way to find out
what was going on. Emergency services would face serious
challenges. While the magnetic fields would probably not
short out individual electronics devices like
cell phones or
computers, communications systems could fail
regionally. In other words, small devices would still
work but would lack the services they require to be
useful.
It's possible that a CME could even affect your
computer and cause glitches. In most cases, a simple
reboot would solve the problem. But with the loss of the
power grid, you'd be limited by your battery's charge.
Once that ran out, you'd be stuck.
There's no way to prevent a solar superstorm but
there are steps we can take to limit the impact of a
CME. One is to overhaul the power grid system. We need a
smart grid that isn't operating so close to capacity as
our current grid. We also need to develop shielding to
protect our electrical infrastructure from magnetic
fluctuations as much as possible.
Even in these worst-case scenarios, the superstorms
don't wipe out all electrical systems across the planet.
Some regions would remain relatively unaffected. It
would require a solar event of unprecedented magnitude
to wipe out the electrical systems across the planet.
But even a modest CME could demonstrate how vulnerable
we are to the
sun's
magnetic temper tantrums.
Lots More
Information
Related HowStuffWorks Articles
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Great Links
Sources
- Beasley, Sandra. "Look at the Sun."
American Scholar. Summer 2008. Vol. 77,
Issue 3, p. 17.
- Encyclopedia Britannica. "Geomagnetic
field." 2009. (Nov. 2,
2009)http://www.library.eb.com/eb/article-9368
- Encyclopedia Britannica. "Solar flare."
2009. (Nov. 2,
2009)http://www.library.eb.com/eb/article-9068560
- Encyclopedia Britannica. "Solar wind."
2009. (Nov. 2,
2009)http://www.library.eb.com/eb/article-9068567
- Encyclopedia Britannica. "Sun."
Encyclopedia 2009. (Nov. 2,
2009)http://www.library.eb.com/eb/article-54151
- Odenwald, Sten F. "Bracing for a Solar
Superstorm." Scientific American. August
2008. Vol. 299, Issue 2, pp. 80-87.
- Plait, Philip, Ph.D. "Death From the
Skies!" New York: Viking. 2008. pp. 33-66.
- Turner, James. "Solar storms ahead: Is
Earth prepared?" The Christian Science
Monitor. May 6, 2009. pg. 25.
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