BASIN-FORMING IMPACT (Painting 555) THE STORY OF THIS PAINTING
This shows a view of the moon and the early Earth at the time of the formation of giant multi-ring basins on the moon. As a discoverer of the phenomenon of concentric-ring impact basins, I've always had an interest in the formation of these features, although this is my first direct attempt in a painting to show such a titanic event. Our discovery of the features came in the early 1960s, when I was a graduate student working for Dr. Gerard P. Kuiper, one of the founders of modern planetary science, at the University of Arizona. I arrived from Pennsylvania in the summer of 1961, and because of my photographic experience, my assistantship assignment was to work on the publication of the Rectified Lunar Atlas, a book of photos of regions of the entire front side of the moon as seen from directly overhead. These pictures were made by projecting the best photos of the moon (collected by Kuiper from many observatories) onto a three-foot diameter white hemisphere. When an image was projected on the hemisphere, we could walk around it, as if orbiting the moon, and look at any formation as if from overhead. This was especially interesting in the regions around the “edge” of the visible disk of the moon. Since the moon keeps one side to Earth, there are regions near the “edge” of the visible moon that we see only with extreme foreshortening of the features (and we never see the back side). One day several assistants projected a photo with especially good coverage of the east “edge” of the moon, and I was astonished to see that features which had been mapped merely as mountain ridges, formed perfect, concentric rings of cliffs, surrounding an obscure lava patch. For some reason, each ring was about √2 (square root of 2) times as big as the previous one. This was the discovery of what is now known as the Orientale Basin. Once I had seen the Orientale Basin, I began to realize that the other large lava plains on the moon occupied similar basins with less prominent concentric rings and also radial fracture of furrow patterns. Various parts of the these systems, like the Altai Scarp and the radial ridge structure emanating from the Imbrium basin had been well recognized, but no one had recognized the simple, consistent symmetry of the concentric/radial fracture pattern composed of rings with their √2 spacing and the radial furrows – looking something like the fracture pattern of a bullet hitting glass. I took these discoveries to Professor Kuiper and he at once recognized their importance, and we wrote a joint paper about it – my first published scientific paper (Hartmann and Kuiper, 1962, Communications of the Lunar and Planetary Laboratory, University of Arizona). The features were readily recognized as a major class of impact structure, and the term “impact basin” entered the literature for the largest crater-like impact features on the moon and planets. More were discovered on the other moons and planets. (However, I received a letter shortly after our first paper came out, from Kuiper's rival, Nobel prize-winner Harold Urey, who said he couldn't see