Ancient Indian Astronomy : Precession and Dates : Frawley
Reference : Gods, Sages and Kings. Vedic Secrets of an Ancient Civilization by David Frawley
For use with our future discussions on this subject, I am jotting down a few points from this reference.
- Today we hear of the dawning of the “Age of Aquarius”. The point of the vernal equinox – the position of the Sun among the stars on the first day of spring – is approaching the sign of Aquarius (Kumbha).
- This phenomenon is caused by a backward tilting of the earth on its axis, the precession, which changes atthe rate of about 50″ per year and competes the whole cycle of the zodiac in about 25,800 years.
- The astronomy of India has always been sidereal, based on stellar positions, unlike the west which employed a “Tropical” zodiac based on seasonal points.
- Most Indian astronomers place the vernal equinox around 23 degrees from 0 degrees Aries, as of 1950. ie 7 degrees of Piesces.
- While the greek Hipparchus calculated the rate of precession as 36″ per year, the Surya Siddhanta calculated the rate at 54″ which is much closer to the modern measurement of 50.3″ per year.
- Precessional changes are the hallmark of Indian Astronomy.
- A sidereal day is 4 minutes shorter than a regular day and therefore there are 366 sidereal days in a normal year. Thus the precession is built into the Indian calendar.
- Any culture employing the sidereal zodiac will find the position of the equinoxes moving back a week or so every 500 years or about 7 degrees in the zodiac.
- Today, Hindus celebrate the Sun entering the sign of Capricorn around Jan 14th as this is the observable sidereal position, and western tropical calendars use Dec 21st as the date of the western solstice.
- Hindu Sidereal calculations are more complicated than tropical ones. Indian astronomy is a very specialised system that requires precise astronomical observations and shows an ongoing knowledge of the exact placement of the planets and equinoxes relative to the fixed stars. many Vedic rituals are described relative to sidereal calendars.
- About every 1000 years, the equinox is moved back another nakshatram (lunar constellation).
- The nakshatram after which each month (masa) is named, mark the beginning of their respective signs.
- The Hindu months were devised according to a correspondence between nakshatras and the zodiac, revealing a knowledge of both systems.
- In Ancient Indian Texts, the nakshatras are listed in the order of their sequence starting with the constellation that marks the spring (vernal) equinox. Medieval lists begin their listing of the nakshatras with Ashwini. Ancinet lists started with Krittija, showing the equinox at the beginning of taurus.
- Whenever the equinox retreated back to a previous sign and therfore a previous month, a major calendar reform was initiated. (We can find various texts and tables in use even today).
- Eras when the equinox came to an initial point of one of the 12 signs were more prominently marked in Vedic texts than the intermediary points.
- For the purpose of Vedic Yajnas, the year began with the winter solstice when the sun was “renewed”.
- The first month of the year therefore becomes, the one named after the nakshatram that marks the full moon on the winter solstice day.
- Vedic literature tells us some of the months named by these lunar constellations (nakshatrams) and the days within them in which the solstices occured, affording us additional means of calculating these eras.
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