A historian has discovered that a 16th-century printed edition of the Almagest — an ancient and influential astronomical treatise — includes numerous handwritten footnotes by Galileo Galilei, the astronomer who later challenged the geocentric view of the universe presented in that treatise. Courtesy of the National Central Library of Florence.

A historian has discovered that a 16th-century printed edition of the Almagest — an ancient and influential astronomical treatise — includes numerous handwritten footnotes by Galileo Galilei, the astronomer who later challenged the geocentric view of the universe presented in that treatise. Courtesy of the National Central Library of Florence.