05-28-2007, 05:32 AM
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When was Jyotishya Shaastra brought to presently used form?
As previously observed, the Earth's Precession makes the Sun move back one degree along the ecliptic in about 76 years with reference to star system. All Sun position references in past with reference to stars on days of Sun singularity, thus carry the astronomical time mark. Bhaarateeya Jyotishya shaastra probably was brought to the presently used form, at a time when old vedic chandramana and all other data was integrated with Raashi or Zodiac based concepts. The time at which this was done can be identified using following.
1. Jyotishya Shaastra starts the lists of Nakshatras with Ashwini, suggesting that Sun was at Ashwini on Spring Equinox day in that period.
2. Jyotishya states that Uttara Ayana starts exactly when sun enters Makara (Capricorn) suggesting that Sun was near Uttaraashadha on Winter Solstice day (Gregorian Dec 21).
Sic'Yasmin Kshane sooryam gachati Makaram; tatah prabhruti shanmasa udagayanam. from Rudra Skanda Bashya (10th century AD) of Khadhira Grihya Sutra (4 century BC).
Use of Load Star Pro and scan of Sun position over past few thousand years yields following results. Figure 16 shows the position of Sun on Spring Equinox day of 400BC (March 21).
The sun is on equator and is clearly at Ashwini Nakshatra. This explains as to why Jyotsihya Shaastra starts the nakshatra list from Ashwini. The figure showing the position of Earth, Sun on Spring Equinox Day in previous section also confirms the fact that Sun would at Ashwini. As already illustrated now sun is at Poorva Bhadrapada. Nakshatra listing today must start from Poorva Bhadrapada.
Figure 17 shows the position of sun on Gregorian December 21(winter Solstice),the start of Uttara Ayana in 400 BC. Clearly the sun is at +23.5 degrees and near Uttara Aashadha near Makara Raashi. This supports the Jyotishya statement that Uttara Ayana occurred when Sun entered Makara near about 400 BC.
Compare this to figure 18, which shows the position of sun on December 21, 1998. Thus sun is clearly at Dhanu Raashi and not at Makara.
Thus the twin observations of Jyotishya Shaastra, (of the Spring Equinox and Winter Solstice) are valid only near 400 BC and hence that is the period when it probably took the present form. It is clear that Bharateeya astronomers who knew of the astronomical information carried down from vedic culture, looked at Western Zodiac based system and then merged the two to form present Jyotishya Shaastra. Hence Jyotishya uses both the 27 Nakshatra's and 12 raashi's.
It should be noted that the Western Zodiac system appears to have been frozen at same time period. It uses Aries as the starting Zodiac in recognition of Spring Equinox occurring at time of entry of Sun to Aries.
When was Jyotishya Shaastra brought to presently used form?
As previously observed, the Earth's Precession makes the Sun move back one degree along the ecliptic in about 76 years with reference to star system. All Sun position references in past with reference to stars on days of Sun singularity, thus carry the astronomical time mark. Bhaarateeya Jyotishya shaastra probably was brought to the presently used form, at a time when old vedic chandramana and all other data was integrated with Raashi or Zodiac based concepts. The time at which this was done can be identified using following.
1. Jyotishya Shaastra starts the lists of Nakshatras with Ashwini, suggesting that Sun was at Ashwini on Spring Equinox day in that period.
2. Jyotishya states that Uttara Ayana starts exactly when sun enters Makara (Capricorn) suggesting that Sun was near Uttaraashadha on Winter Solstice day (Gregorian Dec 21).
Sic'Yasmin Kshane sooryam gachati Makaram; tatah prabhruti shanmasa udagayanam. from Rudra Skanda Bashya (10th century AD) of Khadhira Grihya Sutra (4 century BC).
Use of Load Star Pro and scan of Sun position over past few thousand years yields following results. Figure 16 shows the position of Sun on Spring Equinox day of 400BC (March 21).
The sun is on equator and is clearly at Ashwini Nakshatra. This explains as to why Jyotsihya Shaastra starts the nakshatra list from Ashwini. The figure showing the position of Earth, Sun on Spring Equinox Day in previous section also confirms the fact that Sun would at Ashwini. As already illustrated now sun is at Poorva Bhadrapada. Nakshatra listing today must start from Poorva Bhadrapada.
Figure 17 shows the position of sun on Gregorian December 21(winter Solstice),the start of Uttara Ayana in 400 BC. Clearly the sun is at +23.5 degrees and near Uttara Aashadha near Makara Raashi. This supports the Jyotishya statement that Uttara Ayana occurred when Sun entered Makara near about 400 BC.
Compare this to figure 18, which shows the position of sun on December 21, 1998. Thus sun is clearly at Dhanu Raashi and not at Makara.
Thus the twin observations of Jyotishya Shaastra, (of the Spring Equinox and Winter Solstice) are valid only near 400 BC and hence that is the period when it probably took the present form. It is clear that Bharateeya astronomers who knew of the astronomical information carried down from vedic culture, looked at Western Zodiac based system and then merged the two to form present Jyotishya Shaastra. Hence Jyotishya uses both the 27 Nakshatra's and 12 raashi's.
It should be noted that the Western Zodiac system appears to have been frozen at same time period. It uses Aries as the starting Zodiac in recognition of Spring Equinox occurring at time of entry of Sun to Aries.