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ASTRONOMY IN VEDANGA JYOTHISHYA
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Langadha's Time Antiquity |
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RVJ-6, YVJ-8 state that winter solstice occurs when sun & moon ere in conjunction at beginning of Shravishta, and that summer solstice occurs when sun is at middle of snake, which is the deity name of star Aslesha. These always occur in the lunar months of Magha and Shravana.
Sun’s position at winter solstice can provide us the historical time at which Lagadha identified the Solstices because of earth’s precession. We know the precise location of the winter Solstice and summer solstice along the ecliptic. Using the Precessional properties of Sun, it is possible to exactly date time when Lagadha synthesized Vedanga Jyotishya.
By present day calculation, in 2000 AD Shravishta begins at 317o 11’from Spring Equinox. However, at the time of composing Vedanga Jyotishya Lagadha put Shravishta at 270 degrees from spring equinox or the winter solstice. Hence the Sun has precessed 317.2-270=47.2 o.to present time since Lagadha’s Observations. This corresponds to, with 0.013966o/year Precessional movement corresponds to a time gap of 3379 years or puts the time of Lagadha around 1373 BC.
Similarly Aslesha in 2000 AD begins at 130.55 deg. Middle of Aslesha would be 137.2 deg. Summer Solstice occurred in middle of Aslesha, while sun was at 90 degrees, thus indicating 47.2 deg shift in summer solstice. This again corresponds to 1373 BC date. The two figures show sun at –23.5 & 23.5 degrees latitude and at 18 h & 6h sun angle longitude from spring equinox. These correspond to winter solstice and summer solstices in 1379 BC. Figures correspond to Lodestar Pro geocentric sky view in 1373 BC.
The issue of precise location of Shravishta and Aslesha, as declared by Vedanga Jyotishya, as being the same as contemporary Jyotishya definitions is open to debate for some. Every degree error in correctly identifying Lagadha’s Shravishta, results in an error of 71 years in estimation of his time. However, for purposes of this article we accept the contemporary definitions along ecliptic, particularly since present day Shravishta agrees precisely with 1500-year-old Varaha Mihira’s (550 AD) star locations. Thus Lagadha mahatma and the Vedanga Jyotishya can be clearly dated to around 1373 BC
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