Galileo, Sidereus Nuncius

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When Galileo observed the belt and sword of Orion the Hunter, and the Pleiades star cluster on the back of Taurus the Bull, the background of night gave way before his eyes: His telescope resolved an astonishing number of unexpected stars never seen before. 

On one page he shows 36 new stars around the original six of the Pleiades, and on another, 80 new stars near the belt and sword of Orion. What if uncountable stars might exist, much farther away than was previously believed? How plausible would it be for an immense and vastly thick sphere of stars to rotate every 24 hours around a tiny central, stationary Earth?

“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.”
Galileo, Sidereus Nuncius
trans. Albert Van Helden (University of Chicago, 1989).