Credit for Impact Theory

Abstract

In the news focus story "Impact theory gets whacked" (11 October, p. 183), D. Clery summarizes the present conundrum we face in understanding the Moon's eerie isotopic similarity to the Earth. However, it contains one oversight in ascribing the proposal of the giant impact hypothesis to William Hartmann and Donald Davis (1) in 1975. In actuality, two groups developed this idea contemporaneously and both discussed essentially the same idea at a Cornell conference in 1974, at which all four researchers were present. Hartmann and Davis directly acknowledged this in a footnote in their paper.

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