born in 476 A.D. in Ashmaka, lived in Kusumapura and died in 629 A.D. He is called the first of
the great astronomers of the classical age of
His book, the Āryabhatīya, presented astronomical and mathematical theories in which the Earth was taken to be spinning on its axis and the periods of the planets were given with respect to the sun. He affirmed the theory of the heliocentrism.
In this book, the day was reckoned from one sunrise to the next, whereas in his Āryabhata-siddhānta he took the day from one midnight to another. He stated that 1,582,237,500 rotations of the Earth are equal to 57,753,336 lunar orbits. This is an extremely accurate ratio of a fundamental astronomical ratio (1,582,237,500/57,753,336 = 27.3964693572), and is perhaps the oldest astronomical constant calculated to such accuracy.
Showing the lowercase Greek letter
equivalent to “p” in the Roman alphabet
Aryabhata also gave an accurate approximation for pi, the most accurate among those of the ancients. He does not explain how he found this accurate value, but it could be an approximation to half the perimeter of a regular polygon of 256 sides inscribed in the unit circle. In the Aryabhatiya, he wrote:
"Add four to one hundred, multiply by eight and then add sixty-two thousand. The result is approximately the circumference of a circle of diameter twenty thousand. By this rule the relation of the circumference to diameter is given."
In other words, π ≈ 62832/20000 = 3.1416, correct to four rounded-off decimal places.
Reference for the contents above and further information of Aryabhata’s live:
Ziegenbalg J.: Algorithmen, von Hammurapi bis Gödel; Spektrum Akademischer Verlag