Grandson of Tamerlane

Ulug Beg (1407-1449), Grandson of Tamerlane who created the best-equipped observatory in the medieval world. He plotted the position of the moon, the planets, the sun and 1018 other stars with amazing precision, and calculated the length of the year to within 58 seconds (or even less - the earth spun slower then than it does now).
Grandson of Tamerlane