There's a fallacy in our history textbooks that Copernican astronomy was so obviously superior to Ptolemaic astronomy. The truth is, it wasn't. Not on astronom

There's a fallacy in our history textbooks that Copernican astronomy was so obviously superior to Ptolemaic astronomy. The truth is, it wasn't. Not on astronomical grounds, but on philosophical ones. His observations (mountains on the moon, phases of Venus, sun spots, moons of Jupiter) led Galileo to the conviction that the celestial bodies were made from the same materials as terrestial ones. Remember, aether wasn't just the stuff that filled the space between the celestial bodies, it's also what those bodies were supposedly made of, allowing them the rapid daily motion you have to posit if earth is not supposed to rotate. One of the arguments formerly brought forth against terrestial motion gets thereby neatly turned on its head. The problem was that while personally I find this line of reasoning rather convincing, it's not a smoking gun, which led Galileo on his quest for more direct observational evidence, eg his (incorrect) theory of the tides.