(meteorobs) blind spots and black meteors

Fri Dec 3 10:19:50 EST 2004

-----Original Message-----
From: meteorobs-bounces at meteorobs.org [mailto:meteorobs-bounces at meteorobs.org]On Behalf Of Jeff Wilson
Sent: Thursday, December 02, 2004 9:56 PM
To: Global Meteor Observing Forum
Subject: Re: (meteorobs) blind spots and black meteors

Whoa! 1966; that is a good while.  You must have seen the Leonids in 1966 right Pete?  

Pulling the book Fireballs, Meteors, and Meteorites I find the only mention I've ever seen in print about the black meteor.  Mr. Povenmire makes the statement that it may be hard to convince yourself that this black meteor does not exist.  According to him fatigue is the cause of this black meteor and not to hold your breath for your observing partner to call it out.   I get the impression that he and Norman were observing buddies at one time as he writes of Norman's skill at observing etc.

By the way Norman, do you have any little trade secrets as to how one can increase the number observed during a session?

Jeff

----- Original Message ----- 

From: Bias, Peter  <mailto:pbias at flsouthern.edu> V 
To: Global Meteor Observing Forum <mailto:meteorobs at meteorobs.org>  
Sent: Thursday, December 02, 2004 2:02 PM
Subject: RE: (meteorobs) blind spots and black meteors

Hi Norman and all,

I have yet to see a black meteor, although I've been observing since 1966.  I know Norman's experience dwarfs mine (and everybody else's too!) so I know he is seeing something.  My guess is that this is an interpretation event rather than a real meteor.  As an aside, how does one get a +1 or +3 magnitude for black meteors?  Wouldn't these magnitudes necessarily have to be brighter than the surrounding sky and therefore look bright, not black?

  Pete Bias

-----Original Message-----
From: meteorobs-bounces at meteorobs.org [mailto:meteorobs-bounces at meteorobs.org]On Behalf Of Norman W. McLeod III
Sent: Thursday, December 02, 2004 4:16 AM
To: Global Meteor Observing Forum
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 <http://www.dogpile.com/info.dogpl/search/web/%27blind+spot%27+eye> 

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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