Timbuktu, founded around 1100 as a commercial center for trade across the Sahara Desert, was also an important seat of Islamic learning from the 14th century onward. The libraries of Timbuktu contain many important manuscripts, in different styles of Arabic scripts, which were written and copied by Timbuktu’s scribes and scholars. These works constitute the city’s most famous and long-lasting contribution to Islamic and world civilization. This early 18th-century text was written to train scholars in the field of astronomy, a science that Islamic tradition traces back to Adam and to the prophet Idris. The author discusses, among many other aspects of astronomy, how to use the movements of the stars to calculate the beginning of the seasons. He also discusses how to cast horoscopes. The work includes a diagram representing the rotation of the heavens.