From: D. F. Siemens, Jr. <firstname.lastname@example.org>
> 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.
As I understand it, the abstract said that there are two theories for the
origin of the Kuiper belt -- IF it originated during the "Accretional" time
of the solar system then they MIGHT be like comets, and IF it originated as
bits and pieces thrown off from some of the giant planets then they MIGHT be
more like silicate asteroides. Then the abstract says that "to check
the(se) suppositions we need high-resolution visible and near-infrared
spectral data." Or, in other words, they don't know enough (need more data)
about the Kuiper belt to determine if it is composed of icy comets or
"silicate" asteroids. They propose that a space craft be sent to the Kuiper
belt so that this puzzle can be resolved.
Another YEC Astronomer professor has sent the following note:
Allen, the two people that your friend discussed this with (a preacher
and applied physicist) were a bit out of their field and were probably
relying upon somewhat older creation references. I was bothered by the fact
that creation literature seemed to be silent on the Kuiper belt. That is
one reason why I wrote my article on comets (1997 TJ 11(3): 264-273). There
I do discuss the Kuiper belt and the observations that your friend alludes
to and caution fellow creationists that the Kuiper belt may indeed exist,
along with some cautions that it may not.
This is a major paper and it is on the AIG website, so I have to ask
if your friend is so interested in what creationists teach how he missed
this paper after four years. Furthermore, while the Kuiper belt was
suggested 50 years ago, it was not welcomed by astronomers for more than 30
years, because most thought that perturbations of the (as of yet unobserved)
Oort cloud could account for short period comets. It was in the 1980's that
numerical simulations showed that this was not possible, and so the need to
dust off the Kuiper belt about 15 years ago. Therefore your friend's
estimate of how long the Kuiper belt has been a viable theory is overstated.
> > 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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