The False Division of Tropical & Sidereal Astrology
In the first post in this series on The False Division of Tropical & Sidereal Astrology, we talked about some of the surface level assumptions that lead Westerners to reject the idea of sidereal time in favor of the more familiar tropical system. In this post, we discuss the Babylonian roots of Western astrology, and illustrate why there is precedent for using sidereal time with the Western conception of the zodiac. It all starts back in Babylonia, so that’s where we need to go.
The Babylonian Roots of Astrology
Babylonian astrology is arguably the oldest known astrological system in the world. Its influence on Western astrology, though less well-known, is extensive. The origin of modern Western astrology’s characteristics of the signs and planets, the notion of astrological “rulership,” the idea of planets being in their “exaltation” or “fall” in given signs, and much of the lore related to auspicious or nefarious astrological placements and transits, all dates back to the Babylonians (1). And in ancient Babylonia, sidereal calculations were used – see Kenneth Bowser’s extensive work on the historical record demonstrating Babylonian use of sidereal time. (2)
What became the arguably false astronomical foundation of Hellenistic astrology, and led to the mightily persistent false division of tropical and sidereal astrology in the West, was a misinterpretation of plundered Babylonian astronomical tablets. These tablets were seized during the fall of Babylon, in 331 BC, and made their way into the hands of the Greeks – who, importantly, did not yet know about the precession of the equinoxes. The Babylonians, the Indians, the Persians, and many other ancient cultures did. (Hipparchus would come along about a century later and “discover” precession, adding it to Greek astronomical knowledge, but this did not change Hellenistic preference for the tropical zodiac.)
Indian astrologer Partho Banerjee discusses how the Greeks misinterpreted the Babylonian tablets in his “Sidereal or Tropical Zodiac for Astrology, Part 2”(3). (You’ll notice astrology blogs all do this topic of tropical or sidereal astrology in multiple parts because there’s a lot to it, and we’re nerds!). When the Greeks viewed the tablets, they looked to the current sky and saw that the spring equinox was at 8° Aries, and assumed that the astronomical data on them illustrated various attempts to calculate a fixed, permanent vernal equinox. They settled on 8° Aries for the spring equinox – and that became one of the foundational keystones of Hellenistic astrology.
The Persistence of the “Aries Spring Equinox”
8° Aries was of course only one of several points mentioned on those Babylonian tablets – because the Babylonians were not in fact calculating a fixed point. They were tracking the ongoing, gradual shifting of the Sun’s position in Aries at the spring equinox each year, slowly moving from one degree to the next over the course of 72-year periods. Aries 15°, and Aries 10° were also noted on the tablets; the precession of the equinoxes appears to move “retrograde” from the 30° to the 0° of a sign. So really, what the Greeks were looking at was a highly methodological record of astronomical events, a cosmic log of exactly what was happening in the sky – a dynamic, constantly moving canopy of planetary and stellar activity.
After the death of Alexander, the Romans continued the tradition, started by the Greeks, of aligning the vernal equinox with somewhere between 8-10° Aries as a fixed point – again, not understanding that the vernal equinox was in fact moving backwards and had already moved to yet an earlier degree in Aries.
And eventually, to make things simpler, Hellenistic astrologers decided to dial the spring equinox to a straightforward, fixed position of 0° Aries. 0° is cleaner, easier to conceptualize, and befits the “start” of something, doesn’t it? Sure, at one point before the Common Era, the spring equinox did align with 0° Aries (for 72 years, the amount of time allotted to any degree), but it definitely was not at 0° Aries even when the tropical zodiac was first established.
the Solar System & Stars are Always on the Move
Despite the Greeks planting their flag at 0° Aries, the Earth nonetheless continued to wobble and the precession of the equinoxes carried on. Roughly when the Common Era commenced we shifted into the Age of Pisces, and we have been in the Age of Pisces ever since. After all, we wouldn’t be close to the Age of Aquarius if we were not currently in the Age of Pisces; the astrological ages are so named for which constellation the spring equinox is in.
But still, today Western tropical astrologers continue to start the zodiac at 0° Aries and insist the spring equinox is still somehow in Aries, somewhere in a representational, purely symbolic area of the sky – though it is very clearly not. It isn’t possible for there to be two spring equinoxes. The equinox is simply in Pisces and that’s that. (See Part 3 to dig into the astronomy of this assertion.)
Tropical astrologers sometimes say the continued use of an Aries spring equinox, beyond its accurate historical period, was a conscious decision based on the poles. Since the poles were named during the Age of Aries, they reflect the cardinal signs that were on the tropical axis during that astrological era – Tropic of Cancer and Tropic of Capricorn. But this is actually not the case. As with everything else in the sky, the poles have moved, and now they are in different signs than their original names indicate.
What Led to the Carryover of The Aries Spring Equinox Into the Age of Pisces?
What really caused the carryover of the use of Age of Aries spring equinox into the Age of Pisces was twofold – or really, threefold, but we’re only doing two here:
1) Astrology was outlawed by the Catholic Church and fell out of rigorous practice.
2) The rise of the natural sciences meant that observable astronomical data became paramount – and astrology, since it was only being practiced intermittently and by folks who didn’t incorporate all the latest astronomical info, was ridiculed and rejected as a pseudoscience.
In other words, research, debates, and experimentation in astrology ceased for a long period in the West. No one was going to risk their life and livelihood arguing for the merits of calculating charts with the cosmologically current age, as it would associate them with an outlawed practice.
3) There is, in fact, another layer to ancient people’s affinity for Aries as the start of the zodiac that cemented its “natural” place in Hellenistic astrology. And that is the relationship between astrology and the notion of kingship, which was a big deal, both in Babylonia and later, of course, in European monarchies. See our other post on The Sun, The King, and Astrological Rulership to dig more into that topic.
But back to the Church and the Age of Reason. Ironically, the rise and predominance of Christianity itself has ironically been one of the most consistent global signposts that we are, in fact, in the Age of the Pisces, or the Fishes: Christ is of course associated with the Fish, and the Piscean values of sacrifice and notions of “oneness” have been predominant. And so, one of the world’s dominant religions, which is not generally known for its kindness towards astrology, actually displays the symbolic marker of our current astrological age more accurately than the zodiac system most commonly in practice by Western astrologers. It’s bananas!
You can think of Western notions of the zodiac as a very beautiful, old pocket watch that you might find in an antique store full of collectibles. That familiar carousel of twelve characters, who once upon a time were based on the constellations in the sky. Throughout Western history, despite astrology being outcast as illegal and consequently falling out of practice, people have continued to rediscover this curious clock, with its first hour “stuck” at the sign Aries, and have decided to start using it again—without winding its to account for the time lapsed while it was out of use.
Thus, Western astrology is always 23.5° ahead of the events unfolding in the true sky. (Again, precession leads the apparent motion of the Sun, from our perspective on Earth, backwards along the ecliptic, and thus backwards through the signs).
But Astrology is KINDA Science-y, isn’t It?
Once Hipparchus came along the Greeks eventually understood how precession told a much more dynamic story about the earth’s relationship to the Sun and the ecliptic. But Hellenistic astrology nonetheless set its dial to 0° Aries, and that was that. And this split between astronomical knowledge and common practice amongst Western astrologers is partly why astrology has always been ridiculed and marginalized as a pseudoscience in the West (despite its indefatigable popularity). And understandably so. If a system that refers to astronomical activity does not continue to incorporate ongoing observational data that expands and refines the known planetary phenomena influencing its area of practice, it will understandably be viewed as less intellectually robust at the least – or quackery, at worst.
This habit of omitting the Earth’s wobble and the true zodiac reflecting the precession of the equinoxes is all the more frustrating considering that Western astrology does often have a wonderfully robust capacity for incorporating real astronomical data and evolving with it. For contrast, with each of the discoveries of dwarf planets and asteroids that were unknown to ancient astrologers and astronomers, (including Neptune, Pluto, Uranus, Juno, Vesta, and so on), Western astrology has expanded its set of archetypes and associations. But the adherence to the symbolic tropical zodiac remains staunch.
Where do we go From Here
Now, this all sounds quite critical of tropical astrology, and I do not delight in raising hackles. Well, okay, I admit it: I kinda do a little 😉. All I have to say for myself is I have Mercury trine Pluto and I go deep for the truth and won’t let go. So deal with it.
But in any case, astrology originated as a practice based on the actual sky, and it doesn’t quite make sense to only refer to astronomical events for roughly half of our astrological events (the planets) while leaving what the stars are doing on a smudgy, foggy, “representational” plane. Too, it is astrologically ahistorical to be in the current astrological age but use a zodiac from the previous astrological age. During the Age of Taurus, which preceded the Age of Aries, people recognized the spring equinox was in Taurus. And, you will notice that the Taurean themes of agriculture, human settlements, and establishing structures for accumulating resources and stabilizing human activity were preeminent during that age (4).
The big takeaway is that if astrology doesn’t incorporate the astrological ages in our conception of the equinox, the closer we get to the Age of Aquarius, the nearer a full 30° disconnect between the two systems becomes. And as Bowser says, the more urgent it is that we confront our cosmological misalignment in the West. The fundamental question is this: If we think the planets and stars influence and reflect human life on Earth, doesn’t it matter where the planets actually are in the sky?
In this post, we’ve illustrated that the real “cultural issue” at play in the predominance of the tropical zodiac in the West is the incomplete appropriation of a conquered culture’s knowledge system (in this case, the plundering of Babylonian artifacts by the Greeks). The resulting scientific misunderstanding, and the Church’s outlawing of astrology at key points, created a patchwork of foundational elements in Western astrology that contained astronomical errors and astrological assumptions. But the important thing to recognize is that sidereal time is entirely viable in the West and can work with the Western zodiac and Western methods such as representing the solar system and the zodiac in a two dimensional sphere. It’s just a matter of whether you observe the true equinox according to the true astrological age.
And just remember, although all of us in astrology might get tired of debating the merits of various house systems or arguing about whether or not Ophiuchus should be considered “the 13th sign” and, of course, hashing out the difference between tropical and sidereal time – all of this argumentation and discus is a symptom of a healthy discipline. It is good news for people in a field to argue for valid ideas and consider out different perspectives. It’s a sign we’re living in a free society that allows for dialogue, testing of hypotheses, and academic rigor (for now, at least!)
In the next post in this series, we discuss the mechanics of the seasonal aspect of astrology in relation to ecliptic and equatorial time. It’s nerdy – but there are fun graphics to help you visualize the astronomy stuff. Deal with it.
Resources to Check Out
- Powell, Robert. ‘The Ancient Babylonian Sidereal Zodiac and the Modern Astronomical Zodiac.’ https://www.academia.edu/10266886/The_Ancient_Babylonian_Sidereal_Zodiac_and_the_Modern_Astronomical_Zodiac
- Bowser, Kenneth. Western Sidereal Astrology (website). https://www.westernsiderealastrology.com/
- Banerjee, Partho. ‘Sidereal OR Tropical Zodiac for Indian Astrology – Part 2.’ https://www.astrologyofbharat.org/2019/09/sidereal-or-tropical-zodiac-for-astrology-Part2.html
- AquarianSigns. ‘Age of Taurus.’ Sourced Nov. 30th, 2025. https://aquariansigns.com/welcome/the-age-of-taurus/
