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The scoop on solar flares
LONDON (Reuters) -- A massive gas bubble that could cause havoc with power grids, satellite and communication systems hit the Earth's magnetic field early Wednesday. The solar flare erupted from a big sunspot at about 6 a.m. EST Tuesday. Following are some brief details on solar flares: WHAT IS A SOLAR FLARE? Flares are the most violent event in the solar system. A bright hydrogen arc emitting ultraviolet radiation and X-rays erupts from the sun's corona, the outermost layer of the solar atmosphere. Flares are usually associated with sunspots, dark cool areas caused by intense magnetic fields breaking through the sun's surface. Sunspots can send out clouds of electromagnetic plasma, called coronal mass ejections, composed of a hot ionized gas of charged solar particles. The sun goes through 11-year cycles in sunspot activity. The last peak was 2000. WHAT CAUSES A FLARE? Although the effects of solar flares have been studied for years, their cause remains largely a mystery. They occur when energy stored in twisted magnetic fields is suddenly released. More violent flares occur when sunspots group. They throw out charged particles and radiation with the energy of millions of atomic bombs. WHAT CAN SOLAR STORMS DO? Solar flares and CMEs can wreak havoc with cell phones, radio relays, satellite links and power grids on Earth. In addition to their impact on communications and power on Earth, solar flares can pose radiation poisoning danger to astronauts in space. And CMEs can produce dazzling aurora -- the northern or southern lights. If the magnetic field of the cloud points northward, the same as the Earth's magnetic field, the effects are minimal. If the orientation is southward the effects are more dramatic and can cause severe geomagnetic storms. This particular solar cloud was extremely fast but was mostly pointed northward, minimizing its destructive power. PREVIOUS SOLAR FLARES One of the largest previous sunspots ever seen was on April 2, 2001 but the monster flare shot out away from Earth. A solar storm in March, 1989 knocked out the electrical system in all of Quebec and destroyed a large power transformer in New Jersey. SOURCES: www.sec.noaa.gov, http://sohowww.nascom.nasa.gov, www.esa.int Copyright 2003 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
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