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P. H. Schultz (Brown University)
Why did it take until the middle of the 20th century to acknowledge impact cratering on the lunar surface? Most of the requisite physics was known by the 1870's. And experiments with armaments had demonstrated the consequences of kinetic collisions. Although there had been notable advocates, impact cratering was not considered a favored hypothesis. In part it was because ``good science" was on astrometry, i.e., mapping the Moon. Photography also played an important but unexpected role. Stereo images of the Moon presented at the Crystal Palace Exhibition in 1851 brought the lunar craters into the parlors of everyone. And curiosity stimulated popular books and portfolios addressing the ``why" of the Moon, rather than the ``where." As a result, the mystery of cratering was no longer the just the domain of those with telescopes. The next generation of scientists then asked different questions. Consequently, in this case perspective was as important as new technologies. Harvard geologist (Shaler) once concluded that craters on the Moon could not have been formed by impacts because if they were, then there would have been extinctions of life on Earth. Since there had not been extinctions on Earth, he concluded, the craters on the Moon could not be caused by impacts. This was a case of asking the right question but not looking at the implications of his entire proposition. Such a statement provides an appropriate backdrop for the evolution of thought.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.