Galileo’s telescope: history, scientific analysis, and replicated observations

In the summer of 1609, Galileo Galilei started to improve upon the Dutch spyglass. Only a few months were needed to increase the magnifying power of the instrument up to 30 times. This transformation allowed Galileo to perform astronomical observations destined to change the traditional Universe. At present, the Institute and Museum of History of Science of Florence is conducting a research programme on the lenses of early telescopes. Historical research is combined with scientific analyses conducted by the National Institute of Applied Optics in Arcetri, the National Institute of Nuclear Physics in Florence, and the Glass Experimental Station in Murano. The shape and composition of the lenses are studied by applying different techniques. Moreover, the composition of early lenses and scientific glass objects are compared. Finally, Galileo’s observations are checked with an optical replica of Galileo’s telescope held at the Astrophysical Observatory in Arcetri.