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Re: (meteorobs) Re: Zodiacal light

Lew,

> Hey, Joshua: I've NEVER heard of anyone observing these "Lagrange clouds"
> visually... I think as you say though, they have been photographed. They are
> caused by the collection of debris and dust (manmade and celestial) at two of
> the "Lagrange points" in the Earth-Moon system: these points, labeled "L1"
> through "L5", are spots in space where small objects can remain "suspended" by
> gravity, without orbital motion relative to the Earth or moon. My memory is
> weak, but I think the two mentioned in Lodriguss's book are L2 and L3, and they
> precede and follow the moon by 60 degrees along its apparent path in the sky.
> These two spots also have a special long, hard-to-remember name of their own.
> Anyone recall what this name is: I believe it's the name of an astronomer.

that was something we discussed here a few years ago. The name of our
'second moon' is Kordylewski cloud. So far as I know there exists
no photos of that cloud, and it would be a real challange for an
amateur to take a picture of it. If I recall it correct, there are only
density line graphs from the sixties available.

If your are interested, you may have a look at
http://wwwdot be.schuledot de/schulen/wfs/pages/Mondbeobachter/ZweiterMond/ZweiterMond.html
There you find a number of facts and explanations (in German). 
To summarize it:
The Kordylewski cloud is a faint glow about 2 deg in diameter, which may
have an apparent offset of up to 10 deg from the Lagrange point. It's
about half as bright as the zodiacal light and a little more redish.
Observing sites near the equator are preferred. The night sky must be dark
to see the cloud (i.e. moon below the horizon) and the best times are 4-5
days before/after full moon.

The cloud may have been captured already by photographic meteor observers!
So it would be worthwile to check your archive, if you are doing regular
wide-angle photography.

Cheers, Sirko

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*  Dipl.-Inform. Sirko Molau                  *                          *
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