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Written by Daniel
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Wednesday, 24 September 2008 12:18 |
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Our protective shields are failing, captain' By Lester Haines • Get more from this author
Posted in Space, 24th September 2008 14:26 GMT
The Register! The Sun's solar wind output has fallen to the lowest level since "accurate readings" became available, and the drop may have an effect on the natural shielding which protects the solar system from cosmic rays, NASA reports.
The data comes from the venerable Ulysses spacecraft, the joint NASA-European Space Agency mission launched in 1990* to "to study the sun and its influence on surrounding space". Readings indicate "the solar wind's global pressure is the lowest we have seen since the beginning of the space age", according to Ulysses' solar wind instrument principal investigator, Dave McComas.
Specifically, NASA explains: "In 2007, Ulysses made its third rapid scan of the solar wind and magnetic field from the sun's south to north pole. When the results were compared with observations from the previous solar cycle, the strength of the solar wind pressure and the magnetic field embedded in the solar wind were found to have decreased by 20 per cent. The field strength near the spacecraft has decreased by 36 per cent."
Ed Smith, NASA's Ulysses project scientist, said: "The Sun cycles between periods of great activity and lesser activity. Right now, we are in a period of minimal activity that has stretched on longer than anyone anticipated." [Comments] |
