Galileo Manuscript

Description: This single-leaf manuscript is one of the great treasures of the University of Michigan Library. It reflects a pivotal moment in Galileo's life that helped to change our understanding of the universe. In the summer of 1609 Galileo received a description of a telescope which had been developed the year before in the Dutch town of Middelburg by an optician, one Hans Lippershey. Applying his knowledge of optical science, Galileo built such a glass or telescope for himself, and in the draft letter shown below offers his new "occhiale" to the Doge of Venice, pointing out its potential use in warfare. The final letter, revised from this draft, was sent on August 24, 1609. It is in the State Archives in Venice.The lower part of this sheet shows the use to which Galileo put this optical device a few months later. As he viewed the skies on successive evenings in January, 1610, he had noticed several bright objects around Jupiter that changed position from night to night. On this page, he plotted their positions over the course of one week and, when he drew the diagram in the lower right imagining how these movements would look if they were viewed from above Jupiter, he realized that the objects were moons of that planet. This was the first observational data that showed objects orbiting a body other than the earth. -- University Library
Source: View Item Source
Rights: Public Domain