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Research | Space Research | Space Plasma Physics - Solar wind SWAN
SWAN - Solar Wind ANisotropies
The SWAN (Solar Wind ANisotropies) instrument is one of twelve instruments onboard SOHO (SOlar Heliospheric Observatory) satellite. It is a collaboration between Finnish Meteorological Institute and Service d'Aeronomie. Technical Research Centre of Finland was responsible for the construction, mechanics, thermal design, and central processor of the instrument itself.
A solar Lyman alpha radiation is scattered by hydrogen atoms, which flow into the solar system. The scattered radiation is called interplanetary Lyman alpha radiation. SWAN observes interplanetary Lyman alpha radiation from all directions of the sky. Usually SWAN observes three radiation maps of the whole sky per week. In each map the radiation is strongest near the inflow direction of the interstellar hydrogen gas. However, the overall picture of the sky has changed considerably from the solar minimum 1996 to the solar maximum. Theoretical results have shown that this kind of a change can be caused by the solar wind proton flux which varies according to the distance to the heliospheric current sheet.
One new comet was found and the water production rates of several comets have been estimated from SWAN data.
More information:
, tel. +358 9 1929 4640
, tel. +358 9 1929 4658
SOHO - SOlar Heliospheric Observatory
SOHO has been launched to the L1 Lagrangian point between the Sun and the Earth 1.5 million kilometers ahead of the Earth. SOHO observes the Sun continuously. All previous solar observatories have orbited the Earth, from where their observations were periodically interrupted by the Earth. (SOHO poster, 32kB JPEG)
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