A large sunspot has been the site of several major eruptions in recent days,
including one Thursday that was the largest of the series. Charged particles
from the events have been hammering orbital spacecraft.
The storms caused minor glitches on the Sun-watching SOHO
spacecraft and forced scientists to put two of its instruments into "safe mode,"
not unlike an electronic nap.
The sunspot group is "one of the most flaring regions of the last few years,"
said Bernhard Fleck, SOHO Project Scientist with the European Space Agency (ESA).
Sunspots are regions of intense magnetic energy, cooler than the surrounding
solar surface. They're a bit like corks in a shaken bottle of champagne, and
when they cut loose, radiation and matter are flung into space. Flares of visible
light and X-rays are rated M for medium and X for strong, with an accompanying
number that signifies further intensity.
The sunspot group, numbered 720, has delivered 15 M-class flares and five X-class
flares. At around 2 a.m. ET Thursday, it unleashed an X7, one of the most intense
measured in recent years.
"This activity is significant," said NOAA space weather forecaster Bill Murtagh.
"However, it is considerably less intense than the activity observed during
the 'Halloween Storms' of 2003."
The 2003
rampage, which included 10 X-class flares, knocked out two Earth-orbiting
satellites and even crippled an instrument aboard a Mars orbiter.
Some flares are accompanied by coronal mass ejections (CMEs), which are clouds
of charged subatomic particles that race outward at millions of miles per hour.
They can damage satellites and occasionally trip power grids on Earth. No serious
effects have been attributed to this month's storms. But scientists are on watch.
"Even before the peak of the flare, energetic protons were pummeling SOHO as
well as geostationary spacecraft around Earth," Fleck said.
SOHO (Solar and Heliospheric Observatory) is run by ESA and NASA. It and the
geostationary satellites orbit much higher than many other satellite and are
more directly exposed to storms.
SOHO uses stars to guide it and maintain its attitude. In the past, loss of
a guide star could throw the probe into an emergency. A software upgrade was
done in 1999 after such a problem.
"With the improved software, several stars are tracked at the same time, and
losing the primary one is no big deal as long as there are more stars left to
track," Fleck said. Good thing, because these latest tempests have proved challenging.
"During the first few hours of the storm, four stars were lost," Fleck said.
Two of SOHO's instruments were manually put in safe mode by turning down high
voltages, he added.
Residents of the far north have enjoyed fantastic displays of the Northern
Lights during the storm series. The aurora, as they are also known, are triggered
when the solar storms hit Earth's protective magnetosphere, causing charged
particles to stream into the upper atmosphere, where they excite molecules into
glowing.
The residents of the International Space Station are relatively safe from most
solar storms, because they orbit inside the planet's protective magnetosphere.
In general, the Sun is near a minimum of activity
in a roughly 11-year cycle. But sunspots, flares and eruptions can occur anytime
during the cycle. The storminess is likely to subside in coming days as the
sunspot rotates to the back side of the Sun.
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About
the Sun
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The Sun
makes up 99.86 percent of the solar system's mass and provides
the energy that both sustains and endangers us.
 The
Sun is divided into three main layers: a core, a radiative
zone, and a convective zone. The Sun's energy comes from thermonuclear
reactions (mostly converting hydrogen to helium) in the core,
where the temperature can reach 28 million degrees Fahrenheit.
The energy radiates through the middle layer, then bubbles
and boils to the surface in a process called convection. Charged
particles, called the solar
wind, stream out at a million miles an hour.
Scientists estimate
that it takes a few hundred thousand years for photons, the
basic units of light, to escape the Sun's core and reach the
surface. They arrive at Earth about 8-and-a-half minutes later.
If you
stood on the Sun, its gravity would make you feel 38 times
more heavy than you do on Earth. We don't recommend trying.
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the Sun right now!
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