Freedom to Read Week - Galileo Dialogues

In our continuing series to mark Freedom to Read week, we examine one of the great scientific books in history - and the controversy it caused after publication.

From antiquity, the majority of educated people subscribed to the Aristotelian view that the earth was the center of the universe and that all heavenly bodies revolved around the Earth. Using Coperncius’ theories, however, the Italian physicist and mathematician Galileo confirmed the thesis that it is around the sun, not the earth, that the heavenly spheres revolve. In the book Dialgo sopra I due massimi sistemi del mondo (Dialogue Concerning the Two Chief World Systems), published in 1632, Galileo provided a series of diagrams to demonstrate his theory – including one in Book III which clearly depicts the sun being encircled by the then six known planets (see below). His research led to further speculation about the elliptical orbit of the planets and to the theory of the finite nature of the universe.

The year following its publication, Galileo was imprisoned in Rome on a charge of heresy and the Dialogo was formally condemned in 1634 and placed under house arrest for the rest of his life until his death in 1642. His name remained on the Index of Forbidden Books until 1835, though he was not officially rehabilitated by the Church until 1992.