Al-Biruni 973 – 1048

Abu Rayhan al-Biruni was a Persian polymath of the Islamic Golden Age, often counted among the greatest scientific minds in the history of the medieval world. He worked extensively in mathematics, astronomy, geography, mineralogy, history, linguistics, and comparative religion, and accompanied Mahmud of Ghazni's campaigns to the Indian subcontinent, where he composed his celebrated Indica, the most careful study of Indian thought, religion, and society produced anywhere before the modern period. He calculated the Earth's circumference to a high degree of accuracy and entertained the idea that the Earth might rotate on its axis.

Abu Rayhan al-Biruni was born in 973 in the suburb of Kath, capital of the Khwarezmian region in present-day Uzbekistan. Of Persian or Khwarezmian origin, he received an excellent Arabic education and learned Greek, Syriac, Hebrew, and later Sanskrit. After serving the local Khwarezmshahs and the Samanid court at Bukhara he was carried, with Avicenna's circle, to the court of Mahmud of Ghazna around 1017, and accompanied Mahmud's expeditions into northwestern India.

His more than 150 works span almost every science of his age. Among the surviving books are the Chronology of Ancient Nations (1000), an Introduction to the Art of Astrology, the masterful comparative ethnography of the subcontinent known simply as India (Tahqiq ma li-l-Hind, c. 1030), the Canon Mas'udi on astronomy, the Pharmacy (Kitab al-Saydana), and treatises on geodesy, gemstones, shadows, and mathematical instruments. He measured the earth's radius from a single mountain in Pakistan with remarkable accuracy.

Al-Biruni embodied an unusually skeptical and comparative scientific temper: he insisted on direct observation, on cross-checking of testimony, and on the patient understanding of cultures from within their own vocabulary. His India remains a foundational text of comparative religion and historical sociology. He died at Ghazna in 1048.