al-Battani

More than a thousand years ago, on the roof of an observatory in al-Raqqa, an astronomer measured the length of the year to within about two minutes of the modern value. The twenty-first book of Tracing the Scholars of Islam tells the story of al-Battani: forty years observing the sky, a book cited by Copernicus, and a lesson in distinguishing astronomy from superstition about the stars. “… that you may be guided by them through the darknesses of the land and sea.”