Abu Mahmood Khujandi or Abu Mahmud Hamid ibn al-Khidr Al-Khujandi (Persian: ???????? ?????) was a Persian (Tajik) astronomer and mathematician who lived in the late 10th century and helped build an observatory near the city of Ray (near today's Tehran) in Iran. He was born in Khujand (now Tajikistan) about 940 and died in 1000.

The few facts about Khujandi's life that are known come from both his surviving writings and comments made by Nassereddin Tusi. From Tusi's comments it is fairly certain that Khujandi was one of the rulers of the Mongol tribe in the Khudzhand region, and thus must have come from the nobility.

Astronomy

In Islamic astronomy, Khujandi worked under the patronage of the Buwayhid Amirs of Ray, Iran, where he is known to have constructed the first huge mural sextant in 994 AD.^[1]

Al-Khujandi accurately computed the axial tilt to be 23°32'19" (23.53°),^[2] which was a significant improvement over the Greek estimate of 23°51'20" (23.86°)^[3] and still very close to the modern measurement of 23°26' (23.44°).

Mathematics

In Islamic mathematics, he stated a special case of Fermat's last theorem for n = 3, but his attempted proof of the theorem was incorrect. The law of sines may have also been discovered by Khujandi, but it is uncertain whether he discovered it first, or whether Abu Nasr Mansur or Abul Wafa discovered it first.

Notes

References

External links

• History of Islamic Science

de:Abu-Mahmud al-Khujandi fr:Al-Khujandi gl:Al-Khujandi fi:Abu-Mahmud al-Khujandi