Āryabhata is the first of the great astronomers of the classical age of India. He was born in 476 AD in Ashmaka but later lived in Kusumapura, which his commentator Bhāskara I (629 AD) identifies with Pātaliputra (modern Patna).
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. 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. There was also difference in some astronomical parameters.