Roy,
Your post says nothing about the origin of comets, only that the Kuiper
Belt objects may have two sources. Are you assuming that _all_ objects
kicked out of the Kuiper Belt into smallish elliptical orbits have to be
comets? This is not required by the statement that short-term comets
originate in the Kuiper Belt.
Dave
On Wed, 22 Aug 2001 12:14:54 -0700 "Allen Roy" <allenroy@peoplepc.com>
writes:
> From: Todd S. Greene <tgreene@usxchange.net>
> > At my website I have archived a discussion in which the YECs (one
> a
> > preacher and on an applied physics professor) put forward the
> > YEC-honored argument that "evolutionists have no explanation for
> > short-term comets." Seeing the promotion of this blatant error, I
> > immediately pointed out that not only do astronomers (not
> evolutionists)
> > have a good, reasonable explanation for short-term comets (the
> Kuiper
> > Belt), but they have had this explanation since the early 1950s
> (i.e.,
> > for at least 35 years), and -- even worse for their YEC argument
> -- this
> > explanation had been getting empirical verification, due to
> advances in
> > astronomical instrumentation -- beginning in 1992.
>
> Here is an interesting abstract concerning comets and the Kuiper
> Belt which
> indicates a lack of explanation for short-term comets. It was
> supplied to
> me by a YEC astronomy professor.
>
> Title: Why we need detailed visible-range spectral data on Kuiper
> belt
> objects?
> Authors: Busarev, V. V.
> Affiliation: AA(Sternberg State Astronomical Institute, Moscow
> University)
> Journal: American Astronomical Society Meeting 198, #70.05
> Publication Date: 05/2001
> Origin: AAS
> Abstract Copyright: (c) 2001: American Astronomical Society
> Bibliographic Code: 2001AAS...198.7005B
>
> Abstract
>
> Our understanding of Kuiper belt objects (KBOs)' nature may be based
> on two
> general scenarios of their origin. First, they could result
> from early accretional phases of the Solar System ``in situ". Then
> they are
> probably the most primitive and unprocessed bodies among known and
> should be
> mostly icy, with a very low content of silicate component. Second, a
> considerable portion of them (if not a majority) might have been
> thrown by
> Jupiter and other giant planets from their zones of accumulation. If
> so,
> they could include much more silicates (possibly up to 40%). To
> check the
> suppositions we need high-resolution visible and near-infrared
> spectral data
> on Centaurs (as possible `fugitives' from the Kuiper belt) and the
> KBOs.
> Because of faintness of the objects their physicochemical properties
> remain
> still little-known. Visible-range observations of the bodies by
> means of a
> spacecraft approaching to the belt could much help in solving the
> problem.
>
> Visible-infrared spectrophotometric observations of the objects
> showed a
> considerable diversity among them (Jewitt D. & J. Luu, 1998, Astron.
> J.,
> 115, 1667-1670). It hints at a diversity in content of their matter.
> Spectral features of ices could not probably dominate in the visible
> range
> spectra of silicate-bearing KBOs. Reflectance spectra of principal
> gases'
> frosts are mainly flat and featureless in the range (Wagner J. K. et
> al.,
> 1987, Icarus, 69, 14-28). Besides, silicates of KBOs are probably
> oxidized
> and hydrated to a high extent. Highly hydrated main-belt C-class
> asteroids
> have absorption bands at 0.43 and 0.6-0.8 microns (up to about 5%)
> (Vilas F.
> & M. J. Gaffey, 1989, Science, 246, 790-792 and
> Vilas F. et al., 1993, Icarus, 102, 225-231). Similar spectral
> features
> attributed to oxidized and hydrated silicates were also found on
> many M- and
> S-asteroids (e. g., Busarev V. V., 2001, LPSC XXXII, abstract 1927).
> The
> absorption bands are interpreted as caused by electronic processes
> in a bulk
> of oxidized silicates and hydrated clay minerals including
> structural
> OH-groups. Thus, the absorption features may be considered as
> indicators of
> a presence of oxidized and/or hydrated silicates on a solid body
> regardless
> of its position in the Solar System. For these reasons we have
> started
> visible-range spectroscopic observations of Centaurs and the KBOs on
> Russian
> 6-m telescope
>
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