The Astronomer Sultan

The Rasulids were a Sunni Muslim dynasty that ruled what is now Yemen and the Red Sea Coast of the Arabia peninsula from the early 13th century to 1454. Their third sultan, Al-Ashraf Umar II, was only sultan for less than two years, following a 46-year rule by his father, but he used his time as sultan-in-waiting to become highly educated. He understood medicine, mathematics, agriculture, and astronomy.

As an astronomer, he wrote a treatise about astrolabes (a device known to many in the east and the west) and sundials. In it, he describes the making of a qibla compass, designed to determine qibla properly wherever you are—that is, the direction toward Mecca for when you pray—a vitally important point in Islam. Al-Ashraf did not claim in the treatise that he invented it, but it is the earliest mention of a compass for determining qibla found in a medieval Islamic text, so his name is historically linked with its creation.

The qibla compass, of course, is a magnetic compass that points north. That is only the first step, however: once you find north, marks around the dial indicate major cities in which you might find yourself. The position of the city's name on the dial—if that's where you are when it is time to pray—show the compass direction from north that you must face.

Al-Ashraf also wrote one of the earliest known Islamic works on agriculture, a seven-chapter treatise that covers times for planting, cereal crops, seed crops, flowering plants, aromatic plants, vegetables, and even pest control. He lived in what is considered the Islamic Golden Age, and died in 1296.

The qibla compass is used extensively today; now, what about the magnetic compass itself? When was that discovered, and what did the Middle Ages do with it? Let's find out next time.