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