Galileo's handwritten notes found in ancient astronomy text: Discovery sheds new light on how famed astronomer came to lead a scientific revolution.

This article focuses on the discovery of extensive annotations by Galileo Galilei in a 16th-century printing of The Almagest, an ancient astronomy text by Claudius Ptolemy that described a geocentric cosmos. The annotations, likely written around 1590, reveal Galileo’s deep engagement with and critical analysis of Ptolemy’s work, suggesting that his eventual support for heliocentrism was grounded in mathematical reasoning rather than solely philosophical or political motives. The discovery, made by historian Ivan Malara at Italy’s National Central Library of Florence and supported by handwriting experts and scholars, also includes a rare transcription of Psalm 145, indicating Galileo’s practice of prayer before studying the text. This finding offers new insights into Galileo’s intellectual development prior to his revolutionary astronomical observations. [Extracted from the article]