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Oct. 23 — A strong dose of space weather is forecast to hit Earth
Friday,
potentially disrupting
satellite communications and posing a threat to
power grids on Earth. The event also presents a nice opportunity for
anyone
to view sunspots, though safe viewing techniques must be employed to
prevent eye damage.
THE STORM of charged particles
was unleashed by a dark region on the
solar
surface called Sunspot 484. The huge spot, about the size of
Jupiter’s
surface, has been growing for several days and rotating into a position
that now points squarely at Earth.
Another
giant sunspot is brewing, and more storms could be generated.
Sunspots are cooler regions of the sun where magnetic energy
wells up,
often prior to eruptions.
The sunspot let loose a storm of energetic particles, known as a
coronal
mass
ejection, at 3 a.m. ET Wednesday, according to forecasters at the
National Oceanic and Atmospheric Administration. The
expanding cloud is
expected to arrive midday Friday. It could produce a geomagnetic storm
rated G3 on a scale that
goes up to G5.
The activity is expected to generate a colorful aurora, or Northern
Lights,
down to the northern
United States and much of northern Europe.
Meanwhile,
a continuing “coronal hole” is already providing
aurorae farther
north, in
places like Alaska and northern Canada.
The storm comes as the sun is actually in
a declining mode of activity.
An
11-year solar cycle peaked during 2001 and 2002. Sunspots are fewer
now,
and
activity will ramp down during the next three to four years. But,
scientists say, isolated severe space weather can occur
at any time.
“It’s somewhat unusual to have this much activity when we’re
approximately
three
and a half years past solar maximum,” said Larry Combs, a
forecaster
with the NOAA Space Environment Center’s
Space Weather Operations.
“In
fact, just last week, solar activity was very low with an almost
spotless
sun.”
Space weather has hampered satellite communications before.
In 1997, an AT&T Telstar 401 satellite used
to broadcast television
shows
from networks to local affiliates was knocked out during a solar storm.
In
May
1998 a space storm disabled PanAmSat’s Galaxy 4, used for
automated
teller machines and airline tracking services,
among other things.
Another
storm in July 2000 put several satellites temporarily out of contact
and
caused
navigation problems in others.
Warning of impending storms allows satellite operators to reduce the
risk
of damage
to some satellites by shutting down electronics.
Even cell phones can act up during solar storms, causing dropped calls.
In
1989, a solar storm tripped protective switches in Canadian
Hydro-Québec
power company. All of Québec lost power for
nine hours. The problem
nearly
spread to the United States through an interconnected grid. Power
companies
have
since developed programs to safeguard their systems, but experts
say
they remain at risk.
Forecasters said a second
sunspot, developing and about to rotate into
an
effective position on the sun’s surface, could produce additional
stormy
weather over the next couple of weeks. In fact, early Thursday it
unleashed
a major flare of its own,
one that could generate some space weather
near
Earth even though it wasn’t pointed directly at us. That glancing
blow
would arrive late Friday or, more likely, Saturday.
Sunspots can be seen from home with proper, safe viewing
techniques.
Astronomers suggest projecting the sun’s image through binoculars
onto a
white surface. Never
look directly at the sun, however, either with the
naked eye or through binoculars or telescopes.
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