[net.origins] Morris's comments on lunar origin

lew@ihuxr.UUCP (Lew Mammel, Jr.) (04/10/84)

The Apollo findings narrowed the field of earth-lunar origin theories
considerably, but there are still quite a few in the running. The moon
was found to have a substantially different composition than the earth;
enough so that it cannot be consider a broken off piece of it. That still
leaves the co-formation, and capture theories.

Much more was learned about the details of lunar history subsequent
to its actual formation.  the sequence of formation of the maria is
known, and the "Imbrium event" which formed Mare Imbrium some 4e9 yrs
ago was pivotal.  Many other phenomena are dated pre- or post- Imbrium.

One fascinating detail is that the mare were filled with lava several hundred
million years after their formation.  I don't think the reason for this
is adequately understood.

I looked through LUNAR SCIENCE: A POST APOLLO VIEW and was amazed at the
scope of the data that have been brought to bear on questions of lunar
history.  For example, individual microcraters can be dated by the number
of radiation tracks in the glassy pit formed on impact. Of course, counts
of micro-craters are also a time standard.  Some rocks have complex histories
of exposure, burial and impact fusion.

All of this data fits into a general picture, with many rival theories as to
what a layman (me) would regard as details.  It's a compliment to lunar science
that Morris has to focus on its uncertainties about the very origin of the moon
in his effort to throw its competence into doubt.

It's a truism that the more we know, the more we realize we don't know.
Realization of profound ignorance in an area which has been freshly
unveiled is cause for gleeful enthusiasm, not morose despondency.
Advancement into such new areas, which hitherto had been subject only to
pure speculation, hardly casts doubt on the growing body of knowledge
which is being built upon.

	Lew Mammel, Jr. ihnp4!ihuxr!lew