A huge sunspot kicked up a powerful flare Monday that could spark colorful sky lights above Earth Tuesday night or early Wednesday.
The flare was classified as X-3. All X-class flares
are considered major, with the number indicating a degree of severity. Its radiation
traveled at light-speed, arriving at Earth within minutes and, along the way,
swamping a detector on the Solar and Heliospheric Observatory (SOHO)
spacecraft, which monitors the Sun and its storms.
Along with the flare came a billowing cloud of charge particles known as a
coronal mass ejection (CME). Traveling at millions of miles per hour, CMEs take
anywhere from about 17 hours to two or three days to reach Earth.
Scientists expect this CME [animation]
to arrive overnight Tuesday or sometime Wednesday.
Tricky forecast
The CME is likely to trigger the Northern Lights, also known as aurora. These waves and wisps of red, yellow and green are created when charged particles excite molecules in the upper atmosphere, causing them to glow.
People at high latitudes, including northern Europe and the northernmost United
States, are likely to have a chance of spotting aurora, as they have on recent
nights during an ongoing period of heightened solar activity.
Based on the latest analysis of the solar storm and conditions near Earth,
it is doubtful much will be visible from more southerly locations such as Texas,
said Kent Doggett, the forecaster on duty Tuesday at NOAA's Space Environment
Center.
"It may not show up as a very strong shock, but will probably continue
the level of magnetic activity we're already seeing," Doggett said in a
telephone interview. "I expect minor to severe storms."
Doggett expects the cloud of charged particles to arrive early Wednesday Universal
Time (UT), which translates to Tuesday night or perhaps during the predawn hours
Wednesday in North America.
The tempest lifted off of a region of sunspots [image]
catalogued as 720. Sunspots are cool regions of the Sun's surface that harbor
pent-up magnetic energy. When unleashed like a popped cork, light, X-rays and
charged particles are flung into space.
The sunspot group is rotating toward the limb of the Sun and could produce
more major flares before it heads around to the back side in a few days.
During severe space storms, the aurora can sometimes be seen from middle latitudes,
such as the lower United States and Europe. Scientists cannot accurately predict
how far south the lights will dip in any given storm, however. The effect depends
largely on how Earth's magnetic field is aligned as a storm arrives, among other
factors.
"You have to be a little lucky" to see the aurora, said Joe Kunches,
lead forecaster at the Space Environment Center.
Busy stretch
A previous CME that buffeted the planet late Monday into early Tuesday morning
generated strong aurora for residents in Alaska and other parts of the far North.
Good displays were spotted also in Minnesota, and faint colorings were seen
as far south as Maryland. A Chicago resident reported "a great show" even under
the glare of bright city lights.
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, scientists
have learned.
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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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