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Re: (meteorobs) So many long-yellow Leonids...



On Thu, 18 Nov 1999, Asaf Shtull-Trauring wrote:

> Hi,
> 
> I assume some of you have read my message about the
> magnificent storm of Leonids here in Israel. It was
> one of the most amazing things in life (I actually saw
> twice almost 10!!! meteors  in the same time!!!!!!).
> 
> Anyway, a question- there was a time at night where I
> was seeing, and also my friends, many many Yellow-long
> meteors. IS this a special charactersitic of the
> leonids? there were just so many, and I doubt it's
> accidently.
> 
> Thanks, Asaf.
> 

Hi Asaf,

at first, let me introduce myself. My name ist Florian Zschage, I live in
Kiel (yes, the guy from northern germany!), and had my own tremendous
display of "The King of Meteor Showers" last night, thanks to the fact,
that sometimes the clouds show a bit of mercy and, of course thanks to
Rob McNaught and David Asher for their splendid predictions (are these
guys wizards or something?). I am 23 years old, and study physics. You
asked, why there were so many long-duration yellow meteors during a
special time. Let me guess: These special meteors appeared not very long
after the rising of the radiant, am I right?! Maybe...0-1 UT? 

Ok, what you saw was an effect, that has to do with geometry. You know,
why all the meteors come from the sickle of Leo? It is just an effect of
projection, like some snowflakes (does it snow in your country? ;-), that
appear in front of you and spread to all directions, when driving through
a snow storm with a great speed, alright? That's exactly what the earth
did last night, remember? So all Leonids came (or seemed to come) from
just one point, the so called radiant. 

Now, if the radiant is low in the sky, you must imagine yourself, standing
on planet earth, looking at the radiant. You must not look high into
the sky above you, but nearly along the surface of the earth. What
you see now, are just a few meteors, namely that meteors, that "graze" the
atmosphere and slide just over your sky If they were not disrupted, they
would even reenter open space. And, because these meteors lose
height above ground level so unassertively, they don't burn up so
fast...remember - the air is thinner "up there". Don't forget, this works
just, if the Radiant is VERY low in the sky. So you can understand the
very grand appearance of these "special" Leonids. In 1966 (the last - and
even stronger Leonid meteor storm), some scientists in the arctic saw 
hundreds of these  so called "earthgrazers", because the constellation of
Leo remained near the horizon during their observations for the whole
night. Ok, if the radiant rises (if the earth revolves "into the stream"),
the Leonids begin to pour down on you, and as a matter of fact, they
become more numerous, shorter, faster - and hotter (!). That's because the
friction increases, due to more-vertical impact and the collision course,
the earth takes, when the radiant rises. That's why the yellow colour
vanished with the rising of the radiant. 

If you want to learn more about the past (Leonids 1833 - greatest meteor
show in written history, formidable eye witness reports!), present and
future meteor observations, try the "Handbook for Visual Meteor Observers"
sold by the International Meteor Organisation (IMO). But please, don't
feel like you're reading a cheap commercial now, ok? I don't get any of
this money at all... to bad, if I think about it :-)...

Always clear skies and some meteors here and there!

     Greetings,

          Florian Zschage

          Wilhelminenstr. 28
          24103 Kiel

P.S.: We were dancing and singing, too.

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