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A spectacular solar show NASA-GSFC NEWS RELEASE Posted: November 3, 2002
These beautiful but violent solar events are important to solar science and can affect high-technology systems. "Understanding the processes beneath the Sun's surface that drive these eruptions is critical to understanding the Sun's behavior and its influence on our planet," said Dr. Gareth Lawrence of the Catholic University of America, who is stationed at NASA's Goddard Space Flight Center, Greenbelt, Md., as the Operations Scientist for the Large Angle and Spectrometric Coronagraph (LASCO) instrument on SOHO.
"We've observed thousands of CMEs, but none ever looked like this one," said Dr. Stein Vidar Hagfors Haugan of the European Space Agency, a solar scientist with the SOHO program, also stationed at NASA Goddard. SOHO scientists believe a combination of effects from nearby solar structures, SOHO's viewing position, and an enhancement from image-processing techniques produced the dark area resembling a keyhole in the image. A second CME, also seen with LASCO, erupted October 25 and vaguely resembles a corkscrew, with twisted lines bursting from the Sun. According to SOHO scientists, its unusual appearance is due to twisted solar magnetic fields, which steer the flow of the CME plasma. Part of the Sun's interior magnetic field becomes twisted from activity deep inside the Sun. It is eventually ejected from the Sun following an explosive energy release process. Details regarding how the fields become twisted and the exact mechanisms that propel CMEs into space are the focus of intense research activity.
If directed at Earth, the CME plasma is harmless to people but slams into the Earth's magnetic field, distorting it like a jellyfish buffeted by a strong current. The alteration in the shape of the Earth's magnetic field accelerates electrically charged particles (electrons and atomic nuclei) trapped within. The rapidly-moving particles sometimes generate beautiful auroral displays (northern and southern lights) when they collide with the upper atmosphere around the polar regions. The most severe CME impacts cause geomagnetic storms capable of disrupting satellites, radio communications, and power systems. Neither the keyhole nor the corkscrew CME were heading toward Earth, so they aren't expected to produce strong geomagnetic storm effects.
They frequently linger for a week or two and sometimes suddenly erupt, escaping into space. Other times, the plasma slowly drains back to the solar surface under the influence of the Sun's powerful gravity, 28 times stronger than Earth's. More research is needed before solar scientists can agree on what pushes prominences into the corona and why they sometimes fly off into space. Part of the eruptive prominence was Earth-directed, although it did not generate significant storm activity.
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