Recent satellite observations have revealed that the largest breach yet seen in the magnetic field that protects Earth from most of the sun’s violent blasts, reaches reported.
The discovery made last summer by Themis-a fleet of five small NASA satellites was reported by experts on Tuesday (16th Dec 2008).
Scientists have long known that the Earth’s magnetic field which guards against severe space weather are similar to a drafty old house that’s sometimes lets in violent eruptions of charged particles from the sun.
Such a breach can cause brilliant auroras or disrupt satellite and ground communications. Observations from Themis show that the Earth’s magnetic field occasionally develops two cracks, allowing solar wind-a stream of charged particles spewing from the Sun at 1 million mph-to penetrate the Earth’s upper atmosphere.
Later summer, Themis calculated a layer of solar particles to be at least 4000 miles thick in the outer most part of Earth’s magnetosphere, the largest tear of protective shield found so far.” It was growing rather fast,”Themis scientist Marit Oieroset of University of California, Berkely told to an American Geophysical Union meeting in San Francisco.
Such breaches are temporary and the one observed last year lasted about an hour, Oieroset said. Solar flares are a potential danger to astronauts in orbit but generally are not a risk to people on the surface of Earth.
Scientists initially believed the greatest solar breach occurred when the Earth’s and Sun’s magnetic field are pointed in opposite directions. But data from Themis found that the opposite to be true. Twenty times more solar wind passed into the Earth’s protective shield when the magnetic fields are aligned, Oieroset said.
The Themis results could have baring on how scientists predict the severity of solar storms and their effect on power grids, airline, military communications and satellite signals.
COURTESY:The Associated Press(AP)
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