Early System of Nakṣatras, Calendar, Antiquity o Vedic and Harappan Traditions
Indian Journal of History of Science
The fixation of time for Fire-worships and rites was of prime importance in the Vedic traditions. The apparent movement of the Sun, Moon, and a Zodiacal system along the path of the Sun/Moon with nakatras (asterisms or a group of stars) were used to develop a reasonable dependable calendar maintaining a uniformity in observation of nakatras, from which the antiquity of these early traditions could be fixed up. The gvedic tradition recognized the northern and the southern (uttarāyana and
... uttarāyana and dakiāyana) motions of the Sun, referred originally to six nakatras (raised to 28 or 27) including Aśvinī nakatra citing it about 52 times. It recommended the beginning of the Year and a calendric system with the heliacal rising of Aśvinī at the Winter solstice. When Aśvinī was no longer found at Winter solstice because of the anticlockwise motion of the zodiacal nakatras due to precision (not known at the time), the Full-moon at Citrā nakatra in opposition to the Sun at Winter solstice was taken into account as a marker for the Yearbeginning, resulting in the counting of the lunar months from Caitra at the Winter solstice during Yajurvedic Sahitā time. The same system continued during the Brāhmaic tradition with the exception that it changed the Year-beginning to the New-moon of the month of Māgha (when Sun and Moon were together after 15 days of Full-moon at Maghā nakatra), resulting in the corroboration of the statement, 'Kttikā nakatra rises in the east'. The Vedāga-jyautia continued the same counting system from the Newmoon, assigning the beginning of Śravihā segment of the nakatras as the beginning of 5-year Yuga at Winter solstice. The antiquity of these gvedic, Yajurvedic, Brāhmaic and Vedāga-jyautia traditions may be found by comparing the old and new longitudes of nakatras and fixed at 6500 BC, 5000 BC, 2500 BC and 1000 BC respectively after corrections due to visibility error. This system of astronomical dating, based on long uniform pattern of observations, are possible in a culture obsessed with satisfactory domestic cultivation and regular worships. The Harappan tradition around c.2000 BC followed the Yajurvedic tradition of counting of month from the Full-moon in a star in opposition, still prevalent in some parts of North India, unlike New-moon Brāhmaic system in South India. The calendric elements were found to be luni-solar, and in the process, the types of years, months, days, day-lengths, intercalation, seasons, nakatras & nakatra space (aśa, bhāśa), tithis, full-moon & new-moon in a Yuga, eighteen/ nineteen years' cycle for adjustment of synodic tropical year with lunar year have been explained and discussed.