“For the galaxy is nothing else than a congeries of innumerable stars distributed in clusters. To whatever region of it you direct your spyglass, an immense number of stars immediately offer themselves to view, of which very many appear rather large and very conspicuous but the multitude of small ones is truly unfathomable.”
Here as well, the methodological implications of this booklet are as important as its cosmological consequences. Just as Columbus's voyages of discovery revealed the limits of the ancient geographers' knowledge of the earth, Galileo's telescope revealed that previous astronomical knowledge was confined to only a tiny fraction of the heavens. In both cases, these discoveries were made, not by philosophy or scholarship, but by direct, empirical observations. And both sets of observations were made possible, in turn, by technological advances: in navigation on the one hand, in applied optics on the other.
The differences between the two are also instructive. While Columbus proved stubbonly resistant to the idea that he had discovered a new continent, Galileo immediately recognized the philosophical consequences of his discoveries. And while the New World's abundance of outlandish flora and fauna initially rendered European visitors speechless, Galileo could communicate the essence of his findings effectively by means of a few simple images.
Source. Galileo Galilei, Sidereus Nuncius (1610), fol. inserted between gatherings D and E. Image credits: archive-org. Translation: Albert Van Helden (University of Chicago, 1989).
Supplementary resources. This aspect of the Sidereus nuncius is also explored in a brief video by the Museo Galileo.
Text credits. Howard Hotson (December 2018)