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Re: [Methane Hydrate Club] Solar Activity Report for 1/31/03

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  • David <b1blancer1@earthlink.net>
    ... One clarification I need to make : A coronal hole doesn t generate a CME. What a coronal hole does allow is high speed solar wind to escape. The solar
    Message 1 of 2 , Feb 2, 2003
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      >OK filaments as well as holes can cause CMEs. You said it was
      > pointing in the right direction, does this mean towards us? OR close
      > enough to the South pole to combine with my SE idea?

      One clarification I need to make : A coronal hole doesn't generate a
      CME. What a coronal hole does allow is high speed solar wind to
      escape. The solar wind is generated below the corona. The corona
      slows the solar wind down as it passed through it. When there's a
      coronal hole, the solar wind isn't slowed down as it passes through
      the hole. The collapsing filament I mentioned shot off a Coronal Mass
      Ejection (CME) towards us.


      > How do you know if it is headed this way? Can you see it coming
      > and its progressing path as it comes? Also do any of the loops or holes
      > in the Northern Hemisphere of the Sun cause CMEs? Or are the CMEs that
      > come our way mostly directed at us on the central Sun area? It is my
      > thinking that CMEs don't cause SE, but it is caused by steady South
      > currents put into motion by central Sun functions. Walter
      >

      I knew it was headed this way because the Space Environment Center
      said so! ;-) They seem to know what they're talking about. If you
      see an Earth-directed CME on the images from the SOHO satellite
      coronagraph, it looks like a giant, expanding smoke-ring, or halo,
      thus the phrase full-halo CME. Now, the SOHO cameras suffer from the
      same limitation that any camera does, and that it has no depth
      perception. A CME fired off directly away from Earth looks very
      similar to one coming right at us. That's why the folks who analyze
      the ddata from SOHO also look for other indications such as radio wave
      burts, to correlate with the event. If you see a full-halo CME at the
      same time you see a radio burst from the sun, it's a pretty safe bet
      the CME is headed our way. If, on the other hand, you see the CME and
      no other indications of any activity, then it was probably a backside
      event and headed away from us.

      Northern hemispere solar flares and filaments can certainly generate
      CME's. Their exact direction of travel will be directed by the
      magnetic field that's in the area at the time.
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