History Of Indian Astronomy

Some cosmological concepts are present in the Vedas, as are notions of the movement of heavenly bodies and the course of the year. As in other traditions, there is a close association ofastronomy and religion during the early history of the science, astronomical observation being necessitated by spacial and temporal requirements of correct performance of religious ritual. Thus, the Shulba Sutras, texts dedicated to altar construction, discusses basic astronomical concepts such as the cardinal directions. Jyotiṣa Vedānga as the science of observing the heavens in order to correctly perform Vedic sacrifice arises after the end of the Vedic period, during ca. the 6th to 4th centuries BCE, and the work of Lagadha is informed by these earlier traditions.

By the early centuries of the Common Era, Indo-Greek influence on the Vedanga tradition becomes evident with texts such as Romaka Siddhānta and Yavanajataka. Later astronomers mention the existence of various siddhantas during this period, among them a text known as the Surya Siddhanta. But these weren't fixed texts but rather an oral tradition of knowledge, and their content is not extant. The text today known as Surya Siddhanta dates to the Gupta period and was received by Aryabhata.

The classical era of Indian astronomy begins in the late Gupta era, in the 5th to 6th centuries. The Pañcasiddhāntikā (Varahimira, 505 CE) approximates the method for determination of the meridian direction from any three positions of the shadow using Gnomon. By the time of Aryabhata I the motion of planets was treated to be elliptical rather than circular. Other topics included definitions of different units of time, eccentric models of planetary motion, epicyclic models of planetary motion, and planetary longitude corrections for various terrestrial locations.