🚀 go-pugleaf

  'Didn't see the original...

z007400b@bcfreenet.seflin.lib.fl.us (Ralph Silverman) wrote:

>Frank Crary (fcrary@rintintin.Colorado.EDU) wrote:
>:  <dglmal@telis.org> wrote:
>: >Sedimentary rocks would probably not stand up to millions of years of
>: >space.

>: And? There aren't any sedimentary rocks in the existing collection
>: of meteors, and no spectral evidence of such rocks on asteroids.

>: >All indications
>: >> : are that they formed in weightless environments (except for martian and
>: >> : lunar meteorites of cources). 

>: >How do small rocks form without gravity?  

>: Easily. They hit each other and stick. There is no direct evidence of

  Out of a cloud of dust, (small) solid rocks are produced by
dust-particles "hitting and sticking"??  'Sounds dubious.

>: how asteroids formed, but several moons of the outer planets and
>: Shoemaker/Levy-9 indicate that some moons and comets are loosely
>: bound collections of material. So hitting and sticking is quite
>: reasonable. Gravity only becomes relevant when an object has
>: grown to a size of ~100 km.

  What about solid asteroids?  Hitting-and -sticking dust-particles?

>: >...The truth is meteors and
>: >asteroids were apart of something bigger.

  I'd think so..

>: The "truth"? Truth based on what evidence? The spectra of asteroids
>: shows that they were never part of any body larger than about 500 km.
>: Meteors probably do come from larger bodies: Asteroids. But, with
>: the exception of the Mars and Moon meteors, there is no evidence
>: that they were ever part of a body the size of a planet.

  So were asteroids then formed in situ by colliding dust-particles?

>: > I am not sure how the recent Galileo
>: > asteroid fly-bys back this up.

>: Well, the Galileo data does not indicate that Ida or Gaspara were
>: ever part of a larger body, and the data is consistent with the
>: theory that asteroids are left over debris from the formation of
>: the planets. The main anomaly I'm aware of is that the objects
>: which have impacted their surface have a different size distribution
>: than what was expected (i.e. more large impacts relative to small
>: impacts.) Galileo has observed the same thing on Jupiter's moon,
>: Ganymede. So it isn't a process unique to the asteroid belt, just
>: one different from impacts in the inner solar system and from
>: theoretical expectations.

>: >No body is saying that the earth is a part of a destroyed planet. The
>: >theory states that the moon is the reminiscence of a destroyed planet this
>: >also explains why the earth is blessed with such a large satellite.

>: Two problems. First, the Moon's chemical composition resembles 
>: the Earth's mantle, not the bulk composition of the Earth or
>: any other known planet. Second, the Moon's surface has isotope
>: ratios that exactly match the Earths, in contrast to other planets
>: and meteors.

  A Mars-sized planet smote the Earth obliquely, sending a spew of
incandescent matter (including Earth mantle) into orbit.  This
accreted to become the moon.  (read it somewhere)

>:                                                       Frank Crary
>:                                                       CU Boulder

>--
>****************begin r.s. response*******************

>	re..
>		"...Easily..."
>	(posting cited above) ...

>	how long would that take?
>	if the earth formed
> 	that way ...
>	why are these not planets too?

>****************end r.s. response*********************
>Ralph Silverman
>z007400b@bcfreenet.seflin.lib.fl.us

  Grantland