During the Gupta age many achievements were recorded in the field of mathematics and astronomy were cultivated. Illustrious figures like Aryabhatta and Barahamihira flourished during this age. Aryabhatta wrote his treatise Aryabhattiyam in 499 A.D., which was the first to treat mathematics as a separate subject dealing with arithmetic, geometry, algebra and probably trigonometry. He was the first Indian astronomer to discover that the earth was a sphere and rotated on its axis. His calculation of the size of the earth was very near to modern estimation.In his famous book Surysiddhanta he explains that the lunar eclipse was due to the shadow of the earth falling on the moon. His unique contribution to the world of science was to place the value of numbers from 1 to 9 and the use of zero and the consequent evolution of the decimal system. Hence, it is no wonder that the first Indian satellite sent to the space was named after him.Another astronomer and natural scientist was Barahamihira. He divided astronomy into three branches - Tanta (astronomy and mathematics), Hora (horoscope) and Samhita (astrology). His work, Brihat-Samhita is an encyclopedia on astronomy and Brihatjataka and Laghujataka works on astrology. Aryabhatta and Barahamihira were well acquainted with the contemporary Greek astronomy and their works clearly contain many Greek technical terms.Latadeva was a well-known scientist and a disciple of Aryabhatta. He wrote Paulisa and Romaka Siddhanta, Brahmagupta was another famous astronomer and mathematician who anticipated Newton by declaring that "all things fall to the earth by law of nature, for it is the nature of the earth to attract and keep things." His Brahmagupta Sidhanta was a great work.