In what date range BC did the constellations correspond to their original astrological month periods?

How about when the equinoxes were in Aries and Libra?In what date range BC did the constellations correspond to their original astrological month periods?About 2000 years ago. At that time, western astrology (not astronomy) was formalized. And since that time, the facts of science have been completely ignored by astrologers (such as the precession of the equinoxes, details about the planets, facts about the constellations themselves, etc.)In what date range BC did the constellations correspond to their original astrological month periods?Though IAU divided Stellar sphere in to 88 constellations (with Henri Norris Russel' help), Eugene Delporte, basing on similar work by Gould (1875) has drawn the boundaries to all these 88. In their work they never ever considered earlier work on Astronomy %26amp; Astrology. There is clear distinction between the two even in ancient times. Somehow this point is missed with Astronomy as its basis can't be tampered. Modern Astronomy clubs up the two to throw the baby (of ancient Astronomy) with bathwater. It is Institutionalised cussedness that led to many avoidable discrepancies.

1. That 'signs' are different from 'constellations'. In fact they (ancients %26amp; their followers) are made out to be so. While ancient Astronomers lacking in modern methods of instrumentation that gave accurate results, marked them crudely. It is said to be due to difference between 'constellations' and 'signs'. Same is the case with the difference between 'Zodiac' and 'Ecliptic'.

2. Calender is the basic system for which they (ancients) worked for as that was essential as always. There are two systems - Solar %26amp; Lunar systems of Calender. There is a third system though that employs both, making corrections to Lunar system to bring it on par with Solar system.

3. The line drawings were replaced be Delporte into boundaries along R.A. %26amp; Declination lines like the states boundaries in USA.

4. Earlier line diagrams of Constellations used to be simple but hard for measuring constellations. While translating from line drawings, certain stars can be detached to be included in to the next. 'Fomalhaut' that used to be 'Alpha Sculptoris' has now become 'Alpha Pisces Austrini'. 'Theta Ophiuchi' happened to be lying in the 'bowl' marked by Scorpius in the earlier line diagram. No harm will be done if it is left in Scorpius as 'Th Scorpii' or similar and leaving Ophiuchus to lie beyond the line of Ecliptic. But it was made a 13th Constellation of Zodiac or 13th Sign, by IAU that left other 'Signs' unaltered or with minor adjustments.

3. Many of them were not aware of or didn't know the 'precession' to make the correction to the equinoxes. So, the pure Astrologers amongst them continue to view the first point of Aries as that lying in the Pisces now, almost in Aquarius.

I follow the 'National Calender' devised by Indian Government (soon after Independence) taking the best of traditional (ancient) Indian Astronomy with modern methods of Astronomical observations purely for the benefit of a 'Calneder' to aid the observances of festivals of India and such activities. It is an annual publication that can be purchased in a book shop. In my earlier (learning) days as an amateur Astronomer, while going through them I computed how much the 'First point of Aries' got shifted. Working backward at 50"arc per year, I arrived at the true 'start of Aries' ('Maeshaadi') in the year 425 AD {Here is your answer}. When I consulted History, it coincided with Aryabhata's time. He was the greatest Astronomer/Mathematician India produced (His book 'Aryabhateeyam' is with me which I read) who laid down the ground rules for computation of Calender-making. Later a modern day (20th Century) Calender-maker, 'Lahiri' made this correction to equinoxes.

Even Delporte's Constellation boundaries get skewed every year needing complicated mathematical procedure to clearly uphold the boundaries.In what date range BC did the constellations correspond to their original astrological month periods?This is difficult to answer precisely because the modern borders of constellations are not quite the same as what was used back then.



Also, they created "houses" which were centred on the constellations, but were set up so that the time taken by the Sun to cross each one was exactly 1/12 of a year. Therefore, some houses are larger than the constellation bearing the same name.



And in astrology, the house was more important than the constellation.



The best fit seems to be around AD 100 (see calculation below).



The fact that there are 13 constellations in the zodiac (and there were 13 back then as well) but only 12 houses, does not help with the accuracy.



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Roughly 2000 years ago, the "First Point of Aries" moved into Pisces. Since Christ represented (for many) the hope that was brought by the "New Age", the symbol of the fish was often associated with the early sects of his followers (Christianity only became a religion in the 4th century).



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For the Babylonians, the Greeks (and even for my astronomy teacher from the 1960s), the intersection of the ecliptic with the equator was always called the First Point of Aries, even after it had crossed into Pisces.



This leads me to think that the houses (as used in astrology) only came about after the equinox had moved into Aries.



Otherwise, we would talk of the First Point of Taurus.



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I am making the bold assumption that "on the average", the centre of the houses once matched the centre of the constellations. I used the modern boundary (which adds to the inaccuracy) to find the middle date in 2010 (for the Sun, relative to the constellation), shown on the left. On the right is the middle date according to horoscopes prepared in accordance with western astrology.



Jan. 3.5 (Sag) Dec. 7 (difference = 27.5 days)

Feb. 1.5 (Cap) Jan. 5.5 (difference = 27)

Feb. 27.5 (Aqu) Feb 4.5 (difference = 23)

March 30 (Pis) March 6 (difference = 24)

May 1 (Aries) April 5 (difference = 26)

June 2 (Tau) May 5.5 (difference = 27.5)

July 5.5 (Gem) June 5.5 (difference = 30)

July 31 (Can) July 7 (difference = 24)

Aug. 29 (Leo) Aug. 7 (difference = 22)

Oct. 9 (Virgo) Sep. 7 (difference = 32)

Nov. 11 (Lib) Oct. 7.5 (difference = 34.5)

Dec. 5.5 (Sco) Nov. 7 (difference = 28.5)



*Sco = Scorpius + Ophiuchus



The average difference is 27.17 days, which corresponds to 0.07438 of a year.



For the slippage to go completely around (difference = 1 year) would take 25,800 year.



0.07438 * 25,800 = 1919 years



2010 - 1919 = 91

(which I round off to AD 100)