Martin Kemp writes that “the details of Galileo's cratered Moons are difficult to align precisely with actual features”1. I would like to draw readers' attention to the work of Ewen Whitaker2, a selenographer at the University of Arizona. Whitaker reviewed earlier efforts at identifying the features drawn by Galileo, and took special note of the important contributions of Guglielmo Righini, Owen Gingerich and Stillman Drake. He provided side-by-side comparisons of Galileo's drawings with modern photographs taken at the same lunar phases, and these provide striking support for his contention that Galileo did indeed observe, and record, very accurately.
Whitaker had examined the copperplate engravings of the first edition of Galileo's Siderius Nuncius and seven manuscript images, and he commented on “previously unnoticed differences between the manuscript and printed versions of Siderius Nuncius… In the original edition these engravings present a reasonably well-executed appearance, but subsequent editions utilize woodcuts, and the quality deteriorates very rapidly to the point where they are virtually unrecognizable as Moon images. Some of the disparaging remarks made about the drawings undoubtedly stem from examinations of these cruder images”.
Kemp, M. Nature 401, 116 (1999).
Whitaker, E. J. Hist. Astron. 9, 155–169 (1978).