Larxene wrote:*bangs head on the wall*

Okay, it seems I've opened a can of worms. I did not intend to invite a tropical vs. sidereal conversation, but it seems to have created that effect. I can be sued for negligence!

I agree that we should leave out the 'versus', but the original question is inherently about the difference between sidereal and tropical definitions, so that part is unavoidable. And why should we avoid it? It's a major part of the historical development of astrology.

Alright, so these constellations are on the ecliptic. Martin, do you know any historical sources that details the "chief constellations" present around the time the equally sized zodiac was created? Were there only 12 of these?

I'd prefer to let others answer questions directly related to the Mesopotamian period (Konrad?), as it's been a long time since I read about it and it's not a specialist subject of mine (though I'd recommend Rochberg's The Heavenly Writing, Cambridge UP). I believe they had defined more than 12 constellations that were in the zodiac (that is, near the ecliptic), so that the division into 12 was based at least partly on other (calendrical/mathematical) considerations.

This quote from Francesc Rochberg's The Heavenly Writing (noted by Martin) may be helpful. However, the historical development of Mesopotamian constellations is very well described in the link I posted yesterday. (Article by John. H. Rogers)

4.1.1.2 Norming of the Zodiac

"Since Prtolemy's Almagest, the beginning of the zodiac at 0? Aries was fixed in relation to the vernal equinox, which, however moves westward at a constant rate (1/72? per year). The Babylonian zodiac was not counted from the vernal point, but was generally normed by end points of zodiacal constellations, each one counted form 0? to 30?. This implies a ecliptic of 360?, but Babylonian astronomy employed degrees within signs rather than a strictly numerical count of longitudes from 0 to 360.

"Also, the longitudes assigned to the fixed stars were done so arbitrarily with the result that the zero point of the ecliptic did not coincide with the vernal equinox. That the Babylonian zodiac was sidereally fixed implies that regardless of the date the fixed stars do not change their positions (degree of longitude) with respect to the norming point of the ecliptic." (Rochberg, pp. 131-132)

Here is a key point from Rochberg which is at variance with Rumen Kolev and other scholars as to the norming of the Babylonian zodiac which places Aldebaran at precisely 15? of Taurus (termed "The fixed Babylonian zodiac"):

"More precisely, however, we still cannot establish the star that originally served as norming point for the ecliptic. Even were we to assume the vernal point was determined correctly when it was assigned to 10? or 8? Aries, the corresponding dates for those zodiacal norming points cannot be pinpointed, as we do not sufficiently understand the ancient methods used to obtain those values. Comparison against modern values for the longitudes of equinoxes is therefore uninformative for this purpose." (Rochberg, p. 133)

Quoted from Francesca Rochberg, The Heavenly Writing, Cambridge University Press, 2004.

Martin Gansten wrote:

Larxene wrote:*bangs head on the wall*

Okay, it seems I've opened a can of worms. I did not intend to invite a tropical vs. sidereal conversation, but it seems to have created that effect. I can be sued for negligence!

I agree that we should leave out the 'versus', but the original question is inherently about the difference between sidereal and tropical definitions, so that part is unavoidable. And why should we avoid it? It's a major part of the historical development of astrology.

I was under the impression that there would be no difference between them. There are different definitions?

I was mainly asking about constellations...but I guess the position of the constellations would be different with different zodiacs, now that I think about it.



Therese,

Thanks for information. So there were about 17 or 18 constellations according to the Babylonians's catalogue.

Larxene,

You start this thread with a great question. I?d highly recommend Gavin White?s book, Babylonian Star Lore. I believe this will give you a good sense of the living, organic process that went into the formulation and naming of the zodiac.

You end your posts with a quote about the form changing, the essence remaining. I think Mr. White?s book will give you that sense of the essence which underlies the changing forms of astrology.

Phil