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Solar storm ends years of tranquility
1/25/2012
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A solar flare captured on January 23, 2012 [Credit: NASA's Solar Dynamics Observatory]
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This image shows a solar flare as observed by the Atmospheric Imaging Assembly on NASA’s Solar Dynamics Observatory (SDO)
at 04:12 Universal Time (Greenwich Time) on January
23, 2012. The solar surface brightened noticeably as gas was superheated and
magnetically supercharged. You can see a stream of
solar material flowing off into space above the hot spot, likely
solar protons and a coronal mass ejection (CME).
The corona is the Sun's outer atmospheric layer. Solar flares occur in the neighborhood of sunspots
at solar altitudes near this layer. The most distinguishing feature of solar flares is bright
emission from long ribbons on the solar disk. Solar
flares produce sudden bursts of energetic particles and high-energy
radiation that persist for minutes to hours and travel at or near the
speed of light. The energy that drives both solar flares and CMEs
is believed to come from the interplay between the electrically charged
gas in the solar atmosphere and the Sun's local magnetic field at the
site of the event. Magnetic energy is converted to that of particle
acceleration and heat.
NASA measured the high-latitude solar flare on January 23 as M8.7 in intensity, just below the most intense “X class”
of flares. The eruption sent a stream of fast-moving, highly energetic
protons toward Earth, provoking the most intense solar energetic
particle storm since 2003. Spacecraft observed the CME with an initial speed of more than 2,000 kilometers (1,400
miles) per second. It collided with Earth's magnetic field a
little after 10 AM Eastern Time on January 24.
Solar flares and CMEs can affect satellite operations and short-wave radio communications, and can pose some risks to astronauts, but cannot harm humans on Earth. They can provide a small dose of radiation to
passengers on high-latitude flights. They can also bring auroras to high-latitude skies.
According to NASA, the storm was impressive by recent standards, but nowhere near the
maximum intensities often generated at the height of the solar cycle. “I
would expect that we will see more storms like this one or even bigger
as we get closer to solar maximum,” said Michael Hesse, chief of
heliophysics at NASA’s Goddard Space Flight Center.
For Further Study
Sun, Solar activity, Sun-climate connections, Solar magnetic field, Solar storms
Related Web Sites:
NASA's Solar Dynamics Observatory
Solar Flares: What Does It Take to Be X-Class?
Space Weather Prediction Center
The Sun-Earth Connection FAQ
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