Scientists to Present Results of 'Solar Storm' Research; Massive Events Disrupt Power, Cause Aurora Displays
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A giant "bubble" that erupted from the sun--enhancing aurora displays and causing voltage fluctuations on transoceanic communications cables as it rocketed through space has been under study by National Science Foundation (NSF) funded scientists. They will present results of their research at the American Geophysical Union meeting in Baltimore, Maryland, on Tuesday, May 21st, at 8:30 a.m., in session SM21B, Studies of Recent Geomagnetic Storms.
"It's important to study and understand these events now, so we will have the ability to predict future such 'solar storms' whose effects may be far greater," says Sunanda Basu, director of NSF's aeronomy program. To test existing capabilities in space weather forecasts, scientists identified a 'solar storm' in November, 1993. This magnetic storm produced effects only on satellites and other sensitive systems. However, bigger storms are likely during the next rise of the solar cycle, which will peak at the turn of the century.
The project coordinator for the study, National Science Foundation (NSF)-funded physicist Lt. Col. Delores Knipp of the U.S. Air Force Academy, says that on November 3rd and 4th, 1993, U.S. and Japanese spacecraft detected a supersonic eruption from an active region in the sun's atmosphere. The eruption became an interplanetary hitchhiker by catching a ride on a particularly fast stream of material leaving the sun's atmosphere.
Scientists believe this giant "bubble" rocketed through space at speeds approaching 1.5 million miles per hour and encountered the earth's magnetic shield only 60 hours after leaving the solar atmosphere. "In effect, we had an interplanetary 'collision' right in our own front yard," says Knipp.
She notes that earth's dipole field (the field that makes compass needles point toward the polar region) acts as a shield against such solar eruptions. "This protective field is, magnetically speaking, pliable, so it can deform to absorb the shock of such collisions. However, in the process of absorbing the shock, energy from it has to be redistributed," Knipp explains. Data from the study indicate that the deformation associated with this encounter was so severe that satellites normally orbiting within the shield's protective cover were exposed to a hot cloud of material. Energy from the interaction ultimately fueled a magnetic storm that generated large currents in earth's upper atmosphere and induced response currents on the ground.
This is one of the first situations in which scientists have been able to use multiple satellites to follow such an event from the sun through interplanetary space, and into earth's near-space and atmospheric environment.
The research was inspired by the National Space Weather Program (NSWP), a multi-agency effort to improve the nation's ability to forecast solar events and their resulting effects on earth. The NSWP was motivated by the increasing susceptibility of man-made systems to disturbances in the space environment.
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