ABSTRACT
This chapter explores the place that astronomy occupies in Gassendi’s philosophy. Gassendi believed that astronomy should serve as a model for other disciplines in that it formed probable hypotheses based on observation. He also argued for the high probability of Copernican heliocentrism but never made public his support for it. Instead he left room for Tycho’s geocentrism by emphasizing the hypothetical character of astronomical theories. He thus avoided a conflict with the Church. Finally, though he proposed hypotheses compatible with heliocentrism and his own atomism regarding the shaping of the world and the possibility of extraterrestrial life, he failed to ground these hypotheses in experience. In this respect, he was caught in a dilemma between the empiricism that he took from the ideal of astronomy and the need to give a systematic exposition of Epicurean philosophy.
