The Golden Age

Whenever you look at a map, gaze at the stars or take down a phone number, think of Baghdad. Long ago, brilliant scholars in this booming city studied geography, astronomy and mathematics-and made advances that are still relevant today. Great minds from many lands gathered at a Baghdad library called the House of Wisdom, one of many centers of learning in an era know as the Islamic Golden Age.

Star Finder

Islamic astronomers used a tool called an astrolabe as a guide to the sky. By measuring the position of the sun and stars, they could precisely tell the time of the day or night, or predict the moment when the sun would rise in the morning.

To develop the astrolabe, Islamic scholars took a Greek idea, refined it and added many new features to make it more versatile. According to one early astrolabe expert, this all-purpose astronomical instrument had 1,000 uses in all!

New Numbers

At the House of Wisdom, in Baghdad, scholars pored over Indian books on mathematics. These works used a set of ten symbols to represent numbers-not letters of the alphabet, as in Baghdad and Rome. In the early 800s, mathematician Muhammad ibn Musa al-Khwarizmi wrote a book on how to do math using the Indian system. Three centuries later, it was translated into Latin. Eventually, people all over Europe followed Al-Khwarizmi's example-and switched to the "Arabic" numerals we use today.

Master of Medicine

One of the greatest minds in early medicine was Muhammad ibn Zakariya al-Razi (A.D. 865-925). It is said that Al-Razi chose the most sanitary location for a Baghdad hospital by hanging meat in different neighborhoods to see where it took longest to rot. A firm believer in logic and close observation, Al-Razi wrote some 200 books, from a pamphlet on toothaches to a medical handbook that was used in Europe for hundreds of years.