[meteorite-list] Earth Trojan asteroids

From: Dawn & Gerald Flaherty <grf2_at_meteoritecentral.com>
Date: Sat Jun 25 22:19:29 2005
Message-ID: <008901c579f5$76f0fb20$6502a8c0_at_GerryLaptop>

Ah HAH!! I think. Thank you and thank you cause you've answered both
questions. Billiards on a planetary scale. No wonder I never made it in a
pool hall!! Jerry
----- Original Message -----
From: <MexicoDoug_at_aol.com>
To: <grf2_at_verizon.net>; <francisgraham@rocketmail.com>;
<meteorite-list_at_meteoritecentral.com>
Sent: Saturday, June 25, 2005 3:45 PM
Subject: Re: [meteorite-list] Earth Trojan asteroids


> Jerry F. wrote:
> >Francis and List, could someone help me with the L4, L5 points??
> >Jerry Flaherty
>
> Hola Jerry,
>
> L4 and L5: These two zones (it would be a point if it were unstable, but
> you will see that they are stable and hence, zones) are one AU in front
of
> Earth or 1 AU behind Earth.
>
> They are stable: In the case of going co-orbital exactly 1 AU in front
of
> Earth in our orbit (L4), or co-orbital 1 AU behind (L5), Earth, or
anything of
> reasonable planetary size will either pull it back or drag it along. If
it
> is wanders by being pulled back from L4, it gets pushed in an arc right
into
> the Sun, and if it gets dragged along, it gets pulled away from the Sun
> outwards (both pull and push tangents from 1 AU around Earth are directed
exactly
> into or away from the Sun - draw two equal circles, each that pass
through
> the center of the other to convince yourself). Well hypothetically
pushing it
> into the Sun in front, and then the Sun speeds it up and presto it gets
sent
> right back to where it started from, and when Earth pulls it along then
> presto the extra distance pulled outward from the Sun slows it down, and
the
> hypothetical deviation pull from Earth is compensated and it falls back
into its
> place - a stable equilibrium.
>
> If you like algebra & trig instead of my handwaving summary, it is done
here:
> _http://www-spof.gsfc.nasa.gov/stargaze/Slagrng2.htm_
> (http://www-spof.gsfc.nasa.gov/stargaze/Slagrng2.htm)
> and more elegantly here:
> _http://www-spof.gsfc.nasa.gov/stargaze/Slagrng3.htm_
> (http://www-spof.gsfc.nasa.gov/stargaze/Slagrng3.htm)
>
> Each object has the property, on the case of the Earth-Sun-object, that
they
> have an orbit of one Earth year, locked-step in a dance with Earth until a
> collision or huge comet/asteroid or even another star happens by...and 60
> degrees is a magic number because it creates the equilateral triangle of
> connections among the three masses - which is why all the planets could
have these
> regardless of size, within reason.
>
> Of course, it you placed it exactly at the point L4 or L5 itself and the
> Universe were just three bodies, it would stand still. But due to
influences of
> other planets and significant asteroids, you can get little halo like
> oscillatory "orbits" around the frame of reference of the L-point. Just
like
> pushing a pendulum -it doesn't stop...
>
> Pluto wouldn't be a likely candidate to have "Pluto Trojans" in my
opinion
> since Neptune gravity rules out there, for example...but: did you know
that
> Pluto makes two orbits for every three of Neptunes? It's reasoning just
like
> this....catching up loss and pushing back gain equilibrium and that is
why
> those two planets will never collide.
>
> Saludos, Doug
>
>
>
> ----- Original Message -----
> From: "Francis Graham" <francisgraham_at_rocketmail.com>
> To: <meteorite-list_at_meteoritecentral.com>
> Sent: Friday, June 24, 2005 6:21 PM
> Subject: Re: [meteorite-list] Earth Trojan asteroids
>
>
> > 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
> > >
>
>
Received on Sat 25 Jun 2005 10:19:21 PM PDT