Reading about Aries above, it talks about the spring equinox period. I get the impression that Aries begins at the new moon closest to the equinox.
"Elsewhere I have suggested that the Hired Man assumed its role as herald of the spring equinox and the New Year in the mid 3rd millennium (see the Crook)."
I get confused because in sidereal, Aries is now beginning before the spring equinox.
I thought astrology was essentially more earth-based (geared to seasons) than constellation-based. This is a complex topic, but I'm curious how Babylonian astrology supports using the sidereal zodiac today.
You're assuming that all Astrologers are tropical zodiac users. That's not the case. There are many astrologers that use the Sidereal Zodiac. Indian Astrologers Western Sidereal Astrologers of the Fagan School
Many of the ancient Hellenistic Astrologers used the Sidereal Zodiac Vettius Valens was one of them Of course, the Babylonian astrologers used the Sidereal Zodiac
Sidereal Zodiac views the Vernal Point being in Pisces. It's the vernal point that is linked to the Astrological Ages.
When Ptolemy wrote the Tetrabiblos that led to Tropical Zodiac using Astrology, the Vernal Point was at the beginning of Aries much of his description seems to involve constellations You can say that Tropical Zodiac and Sidereal Zodiac coincided at the time
Norming of the Zodiac from pages 131 to 132 of The Heavenly Writing: Divination, Horoscopy, And Astronomy In Mesopotamian Culture by Francesca Rochberg
Since Ptolemy's Almagest, the beginning of the zodiac at 0 degrees Aries was fixed in relation to the vernal equinox, which however, moves westward at a constant rate of (1/72 degrees per year). The Babylonian zodiac was not counted from the vernal point, but was generally normed by the end points of zodiacal constellations, each one counted from 0 degrees to 30 degrees. This implies an ecliptic of 360 degrees, 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 date the fixed stars do not change their positions (degree of longitude) with respect to the norming point of the ecliptic.
The zodiac and the year itself were defined sidereally, so that one year was the time in which they returned to the same position with respect to a fixed star. The year that was counted from vernal equinox to vernal equinox, known as the tropical year, was not distinguished by the Babylonians from the sidereal year. To have done so would have been to recognize the fact that the equinoxes move - the precession of the equinoxes - and this has been ruled out for Babylonian astronomy.
In mathematical astronomical texts, the equinoxes and solstices were also normed sidereally at 10 degrees Aries in system A and 8 degrees Aries in System B. That the cardinal points of the year do not correspond to the zero points of the appropriate signs in the Babylonian zodiac is a result of the sidereal (rather than the tropical) construction of the zodiac. The two systems of Babylonian mathematical astronomy maintained the two norming points throughout the period of their use. As Neugerbauer pointed out, neither the chronological relation between Systems A and B Norms nor the reason for their difference is understood. That both vernal-point longitudes remained sidereally fixed, however, proves precession was not recognized.
The counting of the zodiac signs from Aries is a consequence of the origins of the zodiacal signs in the association between zodiacal constellations and the twelve schematic months of the year. Although the original list of stars in the "path of the moon" began at the end of Aries, specifically, with the Pleiades (choosing an exemplary star with longitude), the zodiac, when it is numerated in texts, begin with Aries. More precisely, however, we still cannot establish the star that originally served as norming point for the ecliptic. Even were we assume the vernal point was determined correctly when it was assigned 10 degrees then 8 degrees Aries, the corresponding dates for these 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.