Galileo

Courtesy of Smithsonian Institution
Libraries, Dibner Library

In the early 1600s, the Italian professor and experimenter Galileo built a new kind of optical instrument he had heard about: a tube containing two lenses that made distant objects appear nearer. He trained his "optic tube" on the heavens, and what he saw challenged a view of the Universe that had endured for thousands of years. The wonders revealed by his telescope would help convince people that the Earth orbited the Sun.

Sun-Centered Universe

Discoveries by Galileo and others suggested that the Earth and the planets circled the Sun. Multitudes of stars never before seen extended outward to a great and unknown distance. The Universe was not small and confined within a starry sphere; it was vast, perhaps even infinite.