[meteorite-list] Three New 'Trojan' Asteroids Found Sharing Neptune's Orbit

From: Larry Lebofsky <lebofsky_at_meteoritecentral.com>
Date: Fri Jun 16 08:51:05 2006
Message-ID: <1150462260.4492a934a483c_at_hindmost.LPL.Arizona.EDU>

Hi, Sterling:

Not to burst your bubble, but a Trojan asteroid is called such because it is
in a stable position with respect to the planet it is co-orbiting with.

There are 5 what are called Lagrange points: L, L2, L3, L4, and L5.

L1 is between the planet and the Sun (but lined up)

L2 is outside the planet and again lined up.

These two are unstable thanks to the pull of the gravity of the planet and the
Sun. I think that there are man-made satellites in both of these, but they
need small rockets to keep them there (I think SOHO is in L1 and that James
Webb telescope will be at L2). Since they are closer or further from the Sun,
their orbital periods would normally be shorter or longer than the Earth's
(Kepler's Laws), but the gravity of the Earth helps a bit.

L3 is on the other side of the Sun (anybody remember Man from Planet X or
Journey to the Far Side of the Sun). Again, not a stable orbit due to the pull
of the Sun and the planet.

Finally, there are L4 and L5 (remember the L5 Society?). L4 is co-orbital with
the planet and 60 degrees in front of it while L5 is co-orbital and 60 degrees
behind. These are fairly stable points (actually regions) which is why there
are the leading and trailing Trojans of Jupiter. I think the four that are now
known for Neptune are all in the leading zone.

Actually, if you look at where the Jupiter Trojans are, they are
actually "clouds," not points. I am not sure of the size of these, but they
can be inclined to the orbit of Jupiter (as in the case of one of the Neptune
ones), slightly closer or further from the Sun, or slightly in front of or
behind the 60 degree point. In the case of Neptune, that is probably a fairly
large volume.

However, I still do not understand where they come up with the idea that they
are more numerous than the asterod belt. All they have are four and yes, there
may be bunches that are net seen because they are small and relatively far
from the precise trojan points, but that is a long way from saying that there
are more though, similar to what Sterling is saying, the volume is huge.

Larry



Quoting "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>:

> Hi, Everybody,
>
>
> I think you know I am not too easily boggled (as in
> "That's mind-boggling!"), but one sentence in this press
> release boggled me: "Evidence suggests that the Neptune
> Trojans are more numerous than... the asteroids in the
> main belt " MORE Neptune Trojans than Main Belt
> Asteroids, Gracie? Did I hear that right?
>
> My first thought was, "Where you going to put them
> all?" and then I realized that if instead of just being in or
> along Neptune's orbit, they are scattered all over Neptune's
> orbital sphere, why, they would cover the surface of a
> sphere with a diameter of 7,500,000,000 miles, and a
> sphere with a diameter of 7,500,000,000 miles covers
> one heck of a lot of real estate! (Way too many zero's
> for this email!) Lots and lots of room to fit those millions
> of big rocks into!
>
> The second realization was that the statement, "The methods
> used to observe the asteroids are not sensitive to objects so far
> out of tilt with the rest of the solar system" is a complete mouthful
> of weasel-words for "We never bothered to point the big tube
> in that direction. Doh." If you never point the scope at where
> they are, your method is solidly 100% non-sensitive to them!
>
> Seriously, all searches are restricted to a band within a certain
> selected number of degrees of the ecliptic on the assumption
> that there are no more highly inclined objects to look for, on
> a statistical likelihood. Guess what?
>
> More Neptune Trojans than Main Belt Asteroids, huh?
> Are any of'em as big as Ceres? At closest approach a bright
> Ceres-sized asteroid at Neptune's distance would be 535
> times dimmer than Ceres is, about magnitude 13, fading
> to 15 or 16 at other parts of its orbit, and if it were a
> reddened object like so many other outer system objects,
> still fainter by another magnitude or so.
>
> It's well to recall the disputed 2003 EL61, discovered by
> Brown with a Big Gun but not announced and by a Spanish
> team with a smaller telescope and announced, and verified by
> getting a shot of it through a lousy 12-inch scope. Bright as it
> was, it should have been discovered long ago but had never
> been noticed, because of the fact that it's OUT OF PLANE!
> Nobody looked...
>
> A slew of big bumpers beyond Pluto, some with moons,
> and a Planet bigger than Pluto... er, CUSE ME, an "object"
> bigger than the Planet Pluto. Now an asteroid belt as big or
> bigger than the Main Belt, of probable planetesimals for those
> Plutonian Planets I posted so tediously about last year... It's clear:
> THE OUTER SYSTEM IS WHERE'S IT'S HAPPENING!
>
> Been thinking about Migrating to Mars?
> Been saying that someday you're going to get in on the
> Mining Boom in the Main Belt?
> Forever threatening to Jump Off for Jupiter?
> Yearning to buy that ticket for the Shuttle to Saturn?
>
> Forget it! It's a Waste of Time!
>
> The Outer Outer System is Where It's Happening!
>
> For further information,
> contact OOSCC (the Outer Outer
> System Chamber of Commerce) at
> http://sww.ooscc.nep.triton.com/ or
> http://sww.ooscc.pl.charon.com/
> or visit one of our many entertaining Expo's
> on a World or Satellite near you.
>
>
> Sterling K. Webb
Received on Fri 16 Jun 2006 08:51:00 AM PDT


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