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A Twisted Tale of Sunspots

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  • Mark A. LeCuyer
    Source: Space Science News February 29, 2000 A Twisted Tale of Sunspots For images, please visit: http://spacescience.com/headlines/y2000/ast29feb_1.htm Two
    Message 1 of 1 , Feb 29, 2000
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      Source: Space Science News
      February 29, 2000

      A Twisted Tale of Sunspots

      For images, please visit:

      Two large sunspots near the Sun's central meridian have developed
      complex magnetic fields. If solar flares erupt from these regions
      Earth could be in for stormy space weather.

      The NOAA Space Environment Center is forecasting a 70% chance of
      significant M-class solar flares from at least one of the two large
      sunspots currently visible on the solar disk. Because of their
      placement on the Sun, like a double-barreled ray gun, these two
      sunspot groups are likely to produce solar flares and coronal mass
      ejections (CMEs) aimed toward Earth. Stormy space weather could be on
      the way sometime during the next 72 hours.

      Solar flares are the biggest explosions in the solar system. A typical
      eruption can release the same amount of energy as millions of
      100-megaton hydrogen bombs all exploding at the same time. The energy
      source for solar flares is the Sun's magnetic field. Whenever the
      magnetic field around a sunspot group becomes twisted and sheared,
      like a stretched and twisted rubber band, an explosive release of
      energy could be just around the corner.

      Space weather forecasters noticed on February 28, 2000, that both of
      the large active regions 8882 and 8891 (pictured above) had developed
      relatively complicated "beta-gamma" type magnetic fields. Most
      sunspots come in pairs with a magnetic field that looks somewhat like
      that of a bar magnet. Magnetic lines of force emerge from one spot
      (the north pole), loop overhead, and come back down to the other
      member of the pair (the south pole). This is called a bipolar or
      "beta-type" field. "Beta-gammas" are bipolar sunspot groups that are
      so complex that no single, continuous line can be drawn between spots
      of opposite polarity. The energy stored in the twisted magnetic field
      lines serves as fuel for solar flares and CMEs. Eruptions occur when
      the fields rearrange to form a simpler, lower-energy configuration.

      Intense M-class and X-class flares can overload electrical power grids
      and cause blackouts if operators do not take precautions. Satellites
      can be damaged or even destroyed when their electronics are saturated
      by charged particles from large flares. A large and famous space storm
      in 1989 induced electrical currents on the ground that caused a
      failure in the Hydro-Quebec electric power system. This prevented 6
      million people in Canada and the US from having electricity for over 9
      hours. The same storm caused the atmosphere to inflate and dragged the
      NASA's Long Duration Exposure Facility satellite to a lower orbit
      earlier than expected.

      Not every Earth-directed eruption causes big problems, however. On
      February 17, 2000, a solar explosion sent a large coronal mass
      ejection (CME) directly toward our planet. Satellite operators and
      power technicians braced for the worst, but not much happened. The
      Earth's magnetosphere did a good job protecting our planet from the
      interplanetary shock wave.

      It remains to be seen whether active regions 8882 and 8891 will
      produce flares and geomagnetic disturbances. If the spots remain quiet
      for a few more days, the Sun's rotation will carry them westward and
      remove Earth from the proverbial cross hairs. The art of predicting
      solar flares is still rudimentary, so it's hard to say what will
      happen in the coming days. Tune in to SpaceWeather.com for daily
      updates about the development of these active regions and for
      information about other space weather activity.

      SOHO (the Solar and Heliospheric Observatory) is a mission of
      international cooperation between NASA and the European Space Agency.
      It is managed by the Goddard Space Flight Center for the NASA
      Headquarters Office of Space Science. For more news and information
      about space weather, please see SpaceWeather.com. Technical
      information about current space weather conditions may be found at the
      NOAA Space Environment Center.


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