Which book by Galileo led to his trial by the Inquisition?

The book by Galileo that led to his trial by the Inquisition was Dialogue Concerning the Two Chief World Systems. Published in 1632, it presented a four-day conversation comparing the geocentric system associated with Ptolemy and the heliocentric system proposed by Copernicus.

Although Galileo formally presented both models, the dialogue strongly favored heliocentrism. Salviati argued for the moving Earth, Sagredo acted as an interested neutral reader, and Simplicio defended traditional Aristotelian ideas. Church authorities judged that the book violated restrictions imposed after the earlier controversy over heliocentrism.

Galileo was tried in 1633 and found “vehemently suspect of heresy.” He was forced to recant, sentenced to house arrest, and had the book placed on the Index of Forbidden Books. The Assayer was an important scientific work, while Two New Sciences was published later and Starry Messenger announced his telescopic discoveries; neither was the book responsible for the 1633 trial.