Historian finds Galileo's annotated copy of the 16th-century Almagest.

Italian historian Ivan Malara identified handwriting likely belonging to Galileo in a 1551 copy of Ptolemy's Almagest held by the National Central Library of Florence, and handwriting experts said the annotations resemble Galileo's writing; Malara plans to submit a paper to the Journal for the History of Astronomy.

Italian historian Ivan Malara examined a 1551 edition of Ptolemy's Almagest and identified marginal notes in handwriting he and other scholars believe likely belonged to Galileo. The National Central Library of Florence announced the discovery and Malara said a paper describing the findings will be submitted to the Journal for the History of Astronomy. Handwriting specialists at the Galileo Museum and the library reported that the annotations closely resembled Galileo's known writing and abbreviation styles. Malara and others noted that the notes appear to date to around 1590, years before Galileo's well-known telescopic observations. Key details: - The book is a 1551 copy of Ptolemy's Almagest held by the National Central Library of Florence. - Ivan Malara identified annotations that he and specialists report are likely by Galileo, based on handwriting, annotation style, and abbreviations. - A transcription of Psalm 145 in the margin is cited as a historical sign linking the notes to Galileo. - The annotations are reported to date to about 1590, roughly 20 years before Galileo's Moon and Jupiter observations and about 40 years before his later house arrest. - Malara has suggested the mathematical study of Ptolemy helped Galileo engage with Copernicus' heliocentric ideas, though that interpretation is presented as his scholarly hypothesis. Summary: The discovery underscores a documented instance of Galileo engaging closely with Ptolemy's mathematical demonstrations and annotations in a 16th-century Almagest. Scholars and institutions involved have reported that the handwriting and internal signs point toward Galileo, and Malara says he will submit a formal paper to the Journal for the History of Astronomy describing the evidence and interpretation.