(meteorobs) blind spots and black meteors

Thu Dec 2 13:23:54 EST 2004

I cant speak for anyone else but I do have to "observe" that my eyes blind spots do not appear as black. Although it is blind the color black is not there.  It's more akin to no color at all, like a nothingness spot.  Unless of course I were to "create" the color black.

Anyone want to do curved meteors next?

Jeff
  ----- Original Message ----- 
  From: Norman W. McLeod III 
  To: Global Meteor Observing Forum 
  Sent: Thursday, December 02, 2004 4:16 AM
  Subject: (meteorobs) blind spots and black meteors

    Unless you have a companion(or video evidence) who is also seeing the same black meteors, I'll assume you are noticing a mechanism of the eye. 

  That makes sense.

    Norman is probably seeing the blind spots in the center of his eyes.  

  I just did a fairly good measurement of my blind spots.  For left eye looking at Saiph (left foot of Orion), Sirius is about 18 degrees to the left.  With Sirius on the meridian both stars were at about the same elevation.  But Sirius is in my blind spot, which measured 5 degrees wide and 7 degrees tall.  The ellipse of blindness is centered about 2 degrees above Saiph.

  For the right eye I used Bellatrix - Aldebaran but had to turn my head a bit to get them on a horizontal line of sight.  Just about the same measurements came out.  The blind spots are thus 18 degrees away from central vision.  No binocular blindness, thank goodness, or else we would all have a dark spot in otherwise good vision.  The spots would be centered about 36 degrees apart straddling central vision.

  Finding out how large my blind spots are and where they are located, I wonder how they would be connected with black meteors.  The meteors have always been points at or near central vision.  Floaters don't move nearly fast enough for me to be satisfied with that explanation either.  While lying down your floaters would be moving even slower.  In standing up, the floaters tend to sink downwards with gravity.  I haven't logged enough hours in planetariums to see a black meteor there.  So, it's still up in the air...

  Norman

    It's nearly impossible to keep your eyes from moving, so as Norman notices the blind spot it moves across his vision and a black spot appears to move across the star field.

    One of the most dramatic experiments to perform is the demonstration of the blind spot
    http://faculty.washington.edu/chudler/chvision.html

    http://www.exploratorium.edu/snacks/blind_spot.html
    http://coglab.wadsworth.com/experiments/BlindSpot/
    http://library.thinkquest.org/J002330/

    need more?
    http://www.dogpile.com/info.dogpl/search/web/%2527blind%2Bspot%2527%2Beye

    Charlie

    Norman W. McLeod III wrote:

      At 09:39 AM 11/20/2004, you wrote:

        Could you "discuss" the black meteor briefly again Norman; or anyone else.
        I've read and long thought that this was simply something similar to a floater in the eye.  Thanks.

        Long trains,
             Jeff W.

      Here is a partial repost I did on 7 Feb 1999 concerning black meteors.  Their frequency seems less that what I originally wrote.  I have heard several possible explanations for them but am not satisfied with any.  Repost begins next :

      I watched the Perseids of 1960 for a couple of hours at max with my best friend at the time.  Late in the second hour I was astonished to see what looked like a meteor with no color at all, and my announcement of having just  seen a black meteor got us both laughing.  It wasn't fatigue-induced either, for I was fully alert.  
      Turns out I have generally seen one, sometimes two, during most of my observing sessions.  Over the years the appearance of black meteors has been linked to fatigue a number of times, but that hasn't been the case with me.  Too bad I haven't been recording them.

      Our reasoning with joviality  was that meteors come in all colors, so why not black ones?  The ones I see are generally Geminid speed with the moving body visible as a point.  I even get an impression of magnitude from them,  perhaps from the size of the black spot compared to the size of star glare.  The majority are magnitudes  +1 to +3 and travel an average of 10 degrees.  I have never seen one move so fast that only a streak was visible (as in the majority of short fast meteors), nor have I ever seen one leave a train (black or otherwise.)  They seem very real to me, but all these years the situation has been a joke.  Perhaps it's time to reconsider?

      Nebulous meteors are plenty real.  Most of them have a bright central body surrounded by an ethereal envelope, and the ones that are also carrying a wake look like moving comets.  Very rare are the ones that have an appearance like a moving planetary nebula with no central body.  In nearly all cases the meteors are slow.  I always mention these in my notes.

      Norman

      Norman W. McLeod III
      Staff Advisor
      American Meteor Society

      Fort Myers, Florida
      nmcleod at peganet.com

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  Norman W. McLeod III
  Staff Advisor
  American Meteor Society

  Fort Myers, Florida
  nmcleod at peganet.com

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