Mohammad Ulugh Beg, the ruler of Transoxiana, and an accomplished astronomer and mathematician
Compiled By: Syed Ali Shahbaz
On March 22, 1394 AD, Mohammad Ulugh Beg, the ruler of Transoxiana, and an accomplished astronomer and mathematician, was born in Soltaniyeh in northwestern Iran. He was the grandson of the fearsome Turkic conqueror, Amir Timur, and was deputy and eventually successor of his father, Shahrukh Mirza, in Central Asia and later parts of Khorasan and Afghanistan. His mother was the virtuous lady, Gowharshad, who built the grand mosque in Mashhad at the shrine of Imam Reza (AS) – the 8th Infallible Heir of Prophet Mohammad (SAWA) – which still bears her name.
Ulugh Beg patronized art, literature and science. In 1428 he built the famous observatory at his capital Samarqand in cooperation with the famous Iranian astronomer, Ghiyasoddin Jamshid. In his observations he discovered a number of errors in the computations of the 2nd century Greco-Egyptian astronomer Ptolemy, whose figures were still being used. His map of 994 stars was the first one since Hipparchus. The crater “Ulugh Beg”, on the Moon, was named after him by the German astronomer, Johann Heinrich von Mädler, on his 1830 map of the Moon.
He also measured the solar year, starting with the Spring Equinox or Nowrouz at 365 days 5 hours, 49 minutes and 15 seconds, making it more accurate than what Copernicus would later estimate. He also determined the Earth's axial tilt as 23.52 degrees, which remains the most accurate measurement to date – more accurate than later measurements by Copernicus and Tycho Brahe, and precisely matching the currently accepted figure. In mathematics, Ulugh Beg wrote accurate trigonometric tables of sine and tangent values correct to at least eight decimal places. His works were written in Arabic and Persian and translated into Latin in 1665.