Except for one thing, I cannot find fault with the information
presented by David Bowman in his most recent e-mail. The one fault I
do find is one I only know about because I read about it. It is not my
field of expertise. Anyway, here it is.
I do not understand why David's model is: "a simple model that has the
initial state of the mass widely distributed in an annular band around
the Sun in independent circular Keplerian orbits with (near) angular
symmetry, and the final state a single planet orbiting the Sun-also in
a circular orbit."
I don't understand this model because it is not my understanding of how
the planets formed.
(1) There was no sun when the planets formed. There was no mass in
Keplerian orbits around the sun. Rather, there was a huge globular
cloud of gas and dust that became "gravitationally bound." As this
whole cloud began collapsing, it squished into a disk (a normal process
for rotating, gravitationally bound stuff) and that's why planets
essentially end up orbiting in a single plane. At some concentration
of matter in the central core and in the disk, "condensation" began IN
MULTIPLE PLACES. The sun formed and the planets formed AT THE SAME
TIME.
(2) In this picture I am not sure whether the mass that ends up in the
planets comes from an annular ring of this disk of matter, or whether
it comes from a more local area. After all, the original cloud was
more globular, and as it collapsed into a disk there was significant
mass concentration from the globular distribution into the disk
distribution. The matter that ended up in the planets may have never
had an annular distribution.
Therefore, David's idea of an annular band of mass in Keplerian orbits
around the sun just isn't correct. And, if the matter for planet
building comes significantly from above plane and below plane mass as
it compresses into the disk (rather than from an annular region of the
disk) then David's model and calculations are not apropos to planet
formation.
Since I am not a planetary scientist I cannot speak with much
authority, but David's model is not the model I am accustomed to
reading in textbooks and magazines such as Astronomy, Sky and
Telescope, and Scientific American.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817