Aryabhata
Aryabhata was an Indian mathematician and astronomer who wrote, at twenty-three, a work that shaped both fields for a thousand years. Born in 476, probably in the region of Ashmaka or near Kusumapura, generally identified with Pataliputra in modern Bihar, he worked during the Gupta period. The Aryabhatiya, completed in 499, is a compressed text of 121 verses in four sections covering astronomical constants, mathematics, time reckoning and the celestial sphere. Its brevity is extreme, since it was designed to be memorised, and it required commentators to unpack. In mathematics he gave a value for pi of 3.1416, accurate to four decimal places, and described it as approaching — which some read as an awareness that it is irrational. He produced a table of sine differences at intervals of 3.75 degrees, introducing the sine function in the form later transmitted through Arabic to Europe, where a mistranslation of the Sanskrit jya produced the word sine. He gave correct formulae for the areas of triangles, summed series of squares and cubes, and set out the kuttaka method for solving linear indeterminate equations, which is still used. His astronomy was more radical. He held that the earth rotates on its axis daily, and that the apparent westward motion of the stars is caused by that rotation — comparing it to a boat moving downstream while the trees appear to move backwards. He explained eclipses as shadows cast by the earth and moon, rejecting the demons Rahu and Ketu of tradition, and gave the length of the sidereal day to within seconds. His work was translated into Arabic in the eighth century. India's first satellite was named for him.
- Lived: 476 CE – 550 CE
- Nationality: Indian
- Roles: mathematician, astronomer
