Solar Wind Shuts Down and Gives Scientists a Unique Research Opportunity

By Keith Cowing
December 20, 1999
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Last May, the normally active solar wind all but shut down for three days. According to Los Alamos National Laboratory: “scientists at the Department of Energy’s Los Alamos National Laboratory and the Massachusetts Institute of Technology watched as the solar wind all but disappeared. The wind, a stream of plasma from the sun that normally buffets the Earth at speeds close to a million miles per hour, suddenly decreased in velocity to
roughly 626,000 miles per hour. At the same time, the particle density of the wind decreased from its typical 5 to 10 protons per cubic centimeter of
space to 0.2 protons per cubic centimeter. The event, which Los Alamos scientists believe was caused by a coronal mass ejection from the sun, has
quickly become one of the mysteries of space weather studies.”

According to NASA: “Earth’s magnetosphere swelled to five to six times its normal size. NASA’s Wind, IMP-8, and Lunar Prospector spacecraft, the Russian INTERBALL satellite and the Japanese Geotail satellite observed the most distant bow shock ever recorded by satellites. Earth’s bow shock is the shock front where the solar wind slams into the sunward edge of the magnetosphere.”

“This event provides a window to see the Sun’s corona directly,” said Dr. Keith Ogilvie, project scientist for NASA’s Wind spacecraft and a space physicist at NASA’s Goddard Space Flight Center, Greenbelt, MD. “The beams from the corona do not get broken up or scattered as they do under
normal circumstances, and the temperature of the electrons is very similar to their original state on the Sun.”

° Press release, Los Alamos National Laboratory

° Press release, NASA Goddard Space Flight Center

° Press release, University of Colorado at Boulder

° NASA Presentation, AGU 1999 Fall meeting

° Solar-Terrestrial Interactions, SpaceRef Directory

° Geophysics and Solar Science Spacecraft, SpaceRef Directory

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