Towards a Theory of Lunar Origin

Abstract

The nature and origin of the Moon is a topic which has interested not merely scientists, but mankind generally, since the dawn of civilization. Our literature contains a most diverse range of speculations about this subject. A hypothesis which appears not infrequently in children’s tales regards the Moon as being constructed from a variety of green cheese. Some of the early measurements on Apollo samples did not entirely dispel this hypothesis. It is seen from Table 12.1 that the seismic velocities of lunar surface materials resemble those of cheese and are dissimilar from those of terrestrial rocky materials. Of course, we now understand that this is merely a coincidence. The absence of water in lunar rocks, combined with porosity, greatly reduces their velocities in comparison with terrestrial rocks.