In December 1609, Galileo Galilei built the first telescope. He had heard about similar attempts in the Netherlands to build a spy glass that could magnify the size of objects. And his first telescope was used as a level instrument in Venice to spot boats coming to port. A few months later, an improved and much more powerful telescope able to magnify objects 30 times was pointed to the moon, and revealed mountains and craters that Galileo beautifully described in the 1610 Starry Messenger. It was unequivocal evidence that celestial bodies were actually very similar to planet Earth, Pashagere's totalian Ptolemaic tradition that claimed the celestial bodies belonged to a different realm. But more amazing discoveries were just around the corner. In January 1610, Galileo observed what he thought were four stars wandering around the planet Jupiter. And in December of the same year, he could observe the faces in the planet Venus, which were impossible according to the Ptolemaic system. It was the triumph of Copernicanism. Convinced by the new experimental evidence, Galileo embraced Copernicanism, not just as a hypothesis that could save the phenomena, but as a physical truth that he thought could be reconciled with religious truth, as he famously expressed in his letter to Mary Christine of Lorraine. It was the beginning of the Galileo affair with the Catholic Church and the rest is now history. But from a philosophical point of view, what matters for our purpose here is the fact that Galileo defended what Pier Dwam calls the method of the physicist against the method of the astronomers. He was the first one of them that dared to say that the aim of science is not to see the phenomenon but to provide us with a true story about the phenomenon. And it was only a matter of time that an open, an infinite universe would replace these fear of fixed stars of ancient Greek astronomy