18 September 2014 - Mission Day: 6866 - DOY: 261

SOURCES OF THE SOLAR WIND? --- "Plumes" of outward flowing, hot gas in the Sun's atmosphere may be one source of the solar "wind" of charged particles. These images, taken March 7, 1996, by the Solar and Heliospheric Observatory (SOHO), show (top) magnetic fields on the sun's surface near the south solar pole; (middle) an ultraviolet image of the 1 million degree plumes from the same region; and (bottom) an ultraviolet image of the "quiet" solar atmosphere closer to the surface. The top image was taken by the Michelson-Doppler Imager/Solar Oscillations Investigation instrument. The center and bottom images were taken by the Extreme-ultraviolet Imaging Telescope (EIT). These images represent the first opportunity scientists have had to see the detailed development over time of the plume structures in which the solar wind is accelerated, at least at the solar poles. Because of SOHO's continuous view of the Sun, scientists have been able to make movies that allow us to understand the relationship between the magnetic field and the polar plumes. SOHO is presently in a halo orbit around a point known as the "L1 Lagrangian point" approximately 930,000 miles (1.5 million kilometers) from Earth, where gravitational forces of the Earth and Sun balance one another.



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