Albert van Helden, Institute for the History and Foundations of Science, University of Utrecht

“Getting the Most Out of Your Telescope in the 17^th Century”

How good were 17th-century telescopes, and what could one see through them? Over the past several decades, historians, scientists, and museum curators have inventoried telescopes, and written sources about them, in collections all over the Western world and even Asia, and a large amount of information has accumulated. This is an attempt at some preliminary conclusions.