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Just as many Americans got back to work after the long Labor
Day weekend, the sun jolted to life as well, unleashing a massive solar flare
just one day after another sun storm sent a stream of particles racing toward
Earth.
The X-class solar flare — the most powerful type of sun
storm— erupted at 6:12 p.m. EDT (2212 GMT) on Tuesday (Sept. 6) and hit its
peak strength eight minutes later, according to a space weather update by the
National Oceanic and Atmospheric Administration (NOAA). The flare occurred less
than 24 hours after another less intense but still dramatic solar storm.
Several different satellites watched the action unfold,
including NASA's Solar Dynamics Observatory, which constantly records
high-definition videos of the sun in several different wavelengths. The Tuesday event registered as an X2.1-class solar flare,
while Monday's storm topped out at a still-powerful M5, NOAA officials said.
Strong solar flares are classified according to a three-tiered system: X-class
flares are the most powerful, M-class are of medium strength and C-class are
the weakest.
Researchers are still taking the measure of the big Tuesday
sun storm. It may also have produced a coronal mass ejection (CME) aimed at Earth,
researchers said, but as of Tuesday evening it was too early to tell.
CMEs are massive clouds of solar plasma that can streak
through space at up to 3 million mph (5 million kph). CMEs that hit Earth can
wreak havoc on our planet, causing disruptions in GPS signals, radio
communications and power grids.
Monday's event, which took place at 9:50 p.m. EDT (0150 GMT
on Tuesday), did spawn a CME. It was a relatively slow one, traveling at less
than 720,000 mph (1.2 million kph), NASA officials said. And even if this cloud
of charged particles hits Earth in a few days' time, it likely won't cause much
damage.
"This CME is not expected to cause significant
geomagnetic storm activity, and further analysis is currently underway to
better refine the CME timing and magnitude," officials at NOAA's Space
Weather Prediction Center wrote in an update Tuesday.
Monday's M5 solar flare erupted from the middle of the sun's
disk as seen from Earth's perspective. The explosion caused a slight increase
in solar energetic protons about 26,000 miles (41,840 kilometers) above the
Earth's surface, NASA officials said.
The powerful storms unleashed on Monday and Tuesday aren't
isolated incidents. Solar activity has been ramping up over the last few months
as the sun has roused itself from an extended quiescent phase in its 11-year
activity cycle.
Just last month, for example, the sun let loose with an X6.9
solar flare, which was the most powerful solar storm since December 2006, NASA
scientists said. That storm, which erupted Aug. 9, also generated a CME, but it
was not aimed at Earth. Another powerful event, an X2.2-class flare, occurred
on Feb. 15 of this year. Tuesday's X2.1 was the third most powerful flare of
2011.
Scientists expect activity in the current cycle — known as
Solar Cycle 24 — to peak around 2013
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