Y?JNAVALKYA

Y?JNAVALKYA> Indian astronomer, perhaps of the second millennium b.c. Y?jnavalkya is one of the foremost figures in the earliest period of Indian astronomy. There is no unanimity about his time, which has been estimated in an indirect manner. His time was considered to have been around 800 b.c., based on the dating of the Shatapatha Br?hma?a—a voluminous prose text from his school, which serves as a commentary on Vedic ritual—by nineteenth-century philologists. These philological theories have been called into question by new archaeological data, and his true period may be the second millennium b.c.

Y?jnavalkya's parents were Brahmaratha and Sunand?. He studied first in the hermitage of Vaishamp?yana and later with B?shkala and Udd?laka. He is credited with the authorship of the Shukla (White) Yajurveda. He is also credited with the school that put together the Shatapatha Br?hma?a. Many dialogues of Y?jnavalkya with his disciples and with rival sages are preserved in the Vedic literature. Legends connect him to the sun; this may be a slanted reference to his discovery of two important facts about the motions of the sun.

In the Shatapatha Br?hma?a, Y?jnavalkya advances two important theories: first, that a cycle of ninety-five years is required to reconcile the lunar and the solar years (indicating that the length of the year was known to a great degree of accuracy); second, that the circuit of the sun is asymmetric in its four quarters. The proportion for the two halves of the year described by him is 176:189. It is interesting that this proportion is also used in describing the asymmetry of the two halves in the Angkor Wat temple in Cambodia (c. 1150). Y?jnavalkya's astronomy is very important in the history of ideas because it pushes the recognition of the ninety-five-year lunisolar cycle and the asymmetry of the year to a much earlier time than has been supposed.

Y?jnavalkya's astronomy belongs to a period in which astronomical knowledge was part of ritual. Complicated geometrical altars were built to represent the year, with facts about the year expressed in terms of number or area within the altar design. Y?jnavalkya is a major figure in early Vedic thought, renowned for his stress on the correspondence between the outer world and the inner world. Many of his dialogues form a part of the narrative of the Brihad-?ranyaka-Upanishad, in which he mentions a preliminary version of the Pur??ic system of cosmology.

Subhash Kak

See alsoAstronomy ; Science ; Vedic Aryan India

BIBLIOGRAPHY

Kak, Subhash. "The Orbit of the Sun in the Brahmanas." Indian Journal of History of Science 33 (1998): 175–191.

——. "Birth and Early Development of Indian Astronomy." In Astronomy across Cultures: The History of Non-Western Astronomy, edited by H. Selin. Dordrecht: Kluwer Academic Publishers, 2000.

Millar, G., and Subhash Kak. "A Brahmanic Fire Altar Explains a Solar Equation in Angkor Wat." Journal of the Royal Astronomical Society of Canada 93 (1999): 216–220.