Cosmic influences on the early history of the lunar surface

It is pointed out that the observed random distribution of low-angle impact craters over the lunar surface rules out the possibility that particles initially responsible for the origin of such craters had, prior to impact, been in heliocentric orbits. The observed facts are more consistent with a view that particles responsible for most of large primary impact at the earliest stage of lunar history were moving with the Earth-Moon gravitational dipole, and may have represented leftovers from the formation of this pair of cosmic bodies. The application of a similar argument to an equally obvious lack of directional effects in Martian cratering is, however, invalidated by a relatively large inclination of the Martian equator to the orbital plane of this planet.Presented at the NATO Advanced Study Institute on Lunar Studies in Patras, Greece, September 1971.Normally at the Department of Astronomy, University of Manchester, England.