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  • Discoveries May Help Redraw Our Model of the Sun
    Posted by Heather Goss 12:54 AM on Mar 15, 2010

    NASA scientists have made a discovery that may play a part in explaining why the Sun experienced such a deep solar minimum the last few years.  In the recent issue of Science, solar physicist David Hathaway reports that parts of the Great Conveyor Belt have been moving at record speeds.  The Great Conveyor Belt describes a system of hot plasma that circulates through the Sun, coming up towards the surface at the equator and then traveling to the poles, before dipping down and moving back to the center. 

    blog post photo
    Image from taken by SOHO's Extreme ultraviolet Imaging Telescope on Sunday, March 14.

    Using the Solar and Heliospheric Observatory (SOHO), Hathaway has been monitoring the plasma as it moves to the poles, "a little like measuring the speed of a river on Earth by clocking the leaves and twigs floating downstream," and found that the belt has seen a significant increase in speed in the last five years.  Typically, the plasma travels at around 10-15 miles per hour, but after 2004, it sped up to 20-30 mph. 

    Strangely, the bottom layer of the belt seems not to be keeping up.  While SOHO can't visually see the bottom layer, it can track it by the speed of of sunspots across the surface, which are supposed to rooted in the lower layer.  In fact, the plasma moving below the surface isn't just moving slower, it's moving at a record-low speed.  This could mean that sunspots aren't actually rooted in that layer, unlike our current model of the Sun, or it could mean that there's something else going on that scientists' don't understand yet.  The Solar Dynamics Observatory, launched in February, will be able to "see" this lower layer through helioseismology. 

    The other strange connection is that this speed-up occurred during the deepest solar minimum in a century, when previously, it was thought that a faster moving belt would create more activity in the Sun.  In other words, we're probably about to see a big shake-up with regard to our knowledge of how the Sun functions in the next year as SDO comes online and Hathaway continues his study of the Great Conveyor Belt. 

    In other news, the Sun's been a busy stellar object this week.  SOHO captured a video of a halo coronal mass ejection this morning, which may reach Earth around March 17.  Last Friday, SOHO watched as two comets felt the overwhelming pull of gravity right into the Sun's hungry mouth.

    Tags: os99, sun, SOHO, NASA, SDO

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