[meteorite-list] Earth Trojan asteroids

Sterling K. Webb kelly at bhil.com
Fri Jun 24 19:53:03 EDT 2005


Hi,

    Thank you, Francis, for supplying the name that slipped through the
cracks in my brain at three o'clock in the morning.  I knew it started
with "K" and was Slavic, but that's as far as my brain went, and my
Googling finger was numb with overuse.
    They were a subject of derision when first announced (by Kordylewski)
in the 1950's, and I'm glad to know they have been verified, a fact I
will tuck into my brain somewhere away from the cracked areas.
    As for the sky conditions, it sounds like 8000 feet up in the
Colorado Rockies to me. Unfortunately, I actually live dead center in the
Mississippi River basin, with its 15,000 feet of perpetual summer haze
deck, humid, roiling air, deep overcasts, visible photochemical smog, and
occasional tornadoes.
    As for observer's luck, I have spent the last five lunar eclipses
that were supposedly "visible" here standing in my front yard wondering
behind which dark and glowering cloud bank it was happening.  I have a
world class collection of photographs of lunar eclipse colors as seen
diffusely refracted by thick clouds.
    Thanks.

Sterling K. Webb
------------------------------------------------------------------
Francis Graham wrote:

> MOON Trojan objects exist.
>   They are the Kordylewski clouds, small faint patches
> of dust, at the L4 and L5 points of the Earth-Moon
> system (not Earth-sun system).  The Kordylewski clouds
> have been photographed, and have even been seen by the
> naked eye under total dark skies. They may be variable
> in their mass and integrated visual magnitude.
>   Very little has been studied about them, very little
> is known about their possible variability, nobody has
> anything like a reflectance spectrum of the dust. They
> remain the closest things about which so little is
> known. They could well be the subject of study of any
> of you who wish to make a contribution to science.
>   One thing is known: unless you are under skies so
> dark the Milky Way is a BRILLIANT band of light, and
> the Gegenschein is easy, and the zodiacal light is an
> obvious swath, unless you are under those kinds of
> dark skies, you have NO hope of seeing the Kordylewski
> clouds.
>
> Francis Graham
>
> --- MexicoDoug at aol.com wrote:
>
> > Hola Rob,
> >
> > Wouldn't that be <= 2/3's  (gibbous) phase = about
> > 66% illumination, and a
> > maximum average sky angle of a  comfortable,high 60
> > degrees max observed angle
> > (+/- the "oscillation")  ...  checking they're
> > equilateral triangles, though
> > intuition might be  wrong?
> > Saludos, Doug
> >
> > En un mensaje con fecha 06/23/2005 6:21:15 PM
> > Mexico Daylight Time,
> > ROBERT.D.MATSON at saic.com escribe:
> > Certainly astronomers  have tried, but small objects
> > at L4 and L5
> > would be hard to see due to a  combination of range
> > (150 million
> > km), poorer phase angle, and a maximum sky
> > elevation of perhaps 45
> > degrees at astronomical twilight -- lower when the
> > sky is darker.
> > It would be an interesting exercise to compute the
> > maximum  size
> > an Earth Trojan could be and still have managed to
> > go  undetected.
> >
> > --Rob
> >
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