The False Dichotomy of the “Tropical vs. Sidereal” Astrology Debate (Pt. 1)

In modern astrology, the question of whether tropical or sidereal astrology is the better system often results in a false “truce.” This truce goes something like this: 

“Sure, sidereal astrology uses the true constellations and accounts for the precession of the equinoxes, but tropical astrology is based on the seasons. Sidereal astrology is Indian and lunar-based, whereas Western tropical is Western and sun-based. They’re two different approaches from two different cultures.” 

This explanation tries to give an equal-sized bouquet of acknowledgment to both parties. The urge to put out the fire of conflict, or defend a practice that feels under attack, is strong. Settling on the idea of two differing but equal cultural value systems, chalking it up to a matter of astrological apples and oranges in other words, is appealing. However, this truce relies on two false dichotomies: One, that the differences between tropical and sidereal just amount to a cultural issue, and second, that one system focuses more on the zodiac whereas the other focused more on the seasons. In this article we’ll break both of these falsehoods down and provide a clear lens on this often grossly overgeneralized and misunderstood topic in astrology. 

 

Dismantling the first false dichotomy: “It’s just cultural”

 

First, the idea that sidereal astrology is only the provenance of Vedic astrologers is false. There is also a healthy strain of sidereal astrology practice in the West — called, it so happens, Western sidereal astrology (1). Vedic astrology’s focus on the Moon (versus Western tropical astrology’s focus on the Sun) is a separate topic from its use of sidereal calculations, and is often used to dismiss sidereal astrology. 

But the decision to use a zodiac that is aligned with cosmological time is not a cultural issue - or at least not the type of cultural issue you might think it is; “East vs. West.” Though Western tropical astrology is far more prevalent in the west, there is a healthy contingent of astrologers throughout modern history who have found it wanting and have migrated to the sidereal system. 

However, this does not have to mean throwing away all the Western mythological and zodiacal lore of the Western zodiac, adopting Vedic names for the planets, and changing one’s whole cultural frame of reference. (Doing so is not only unnecessary, it could also result in some unfortunate cultural misappropriation. Though cultivating respect for different cultural practices and perspectives is healthy, Westerners should probably always be on the lookout for our tendency to consume the cultures of others without sensitivity to its people or understanding of its original context. This type of cultural blindspot and lack of appreciation for the depth of knowledge and systems of inquiry from other cultures is actually key in the origin story of how the Western tropical zodiac came to be, in fact. Read on.) 

 

Sidereal astrology, remember, simply means accounting for the precession of the equinoxes in our astrological calculations. It means our charts are, more or less, aligned with the actual, observable phenomena happening in the sky. (More or less because, as with tropical astrology, there is a wide variety of house systems which are used for various reasons, and the extent to which a sidereal chart reflects exactly what would be displayed on a snapshot of the constellations in the sky varies. Most sidereal house systems do not in fact display the houses in exact proportion to the sizes of the constellations in the sky.) 

 

However, the use of sidereal astrology is not new to the West. It is in fact our original system, and dates back to the Babylonians, from whom Western ideas about astrology originally come. See Kenneth Bowser’s extensive work on elucidating the Babylonian roots of Western astrology in general, which he also shows as the ancient antecedent of modern Western sidereal astrology (2). Sidereal calculations were used in ancient Babylonia for all kinds of calculations, from astronomical to astrological. It was notes made about this sidereal system on astronomical tablets that were plundered during the fall of Babylon, in 331 BC, which made their way into the hands of the Greeks. 

The tropical zodiac became established in the west due to one big misunderstanding. As Indian astrologer Partho Banerjee notes in his “Sidereal or Tropical Zodiac for Astrology, Part 2” (3), when the Greeks received those Babylonian astronomical tablets in 331 BC, the Greeks did not understand that the vernal equinox moved in retrograde motion, and decided that the vernal equinox was (permanently) at 8° Aries. 8° Aries was one of several points mentioned on the tablets (Aries 15°, and Aries 10° also being noted; the precession of the equinoxes, of course, goes back in time to the “beginning,” or 0° mark, of a sign). These tablets, after all, dated from the ancient period when the vernal equinox was passing through Aries. But the Greeks did not understand the equinox is always on the move; although some ancient cultures understood the precession of the equinoxes, the Greeks and Romans did not. Again, to recap: The origin of the tropical zodiac is a misunderstanding of Babylonian astronomical and astrological tablets which depicted the precession of the equinoxes, which was an astronomical phenomenon then-unknown to the ancient Greeks. 

After the death of Alexander, the Romans continued the tradition, started by the Greeks, of aligning the vernal equinox with 8-10° Aries as a fixed point - again, not understanding that the equinoxes were in fact moving backwards and had already moved to an even yet earlier point in Aries. And, as Banerjee notes, all of this happened before Hipparchus, who is the Westerner credited with discovering that the equinox moves. 

Though at one point before the Common Era, the spring equinox did align with 0° Aries (for roughly 72 years, the amount of time allotted to any degree), it definitely was not at 0° Aries even when the tropical zodiac was established. But today, Western tropical astrologers continue to start their zodiac at 0° Aries - even though the equinox had already passed on from this point at the time the tropical zodiac was created! 

From there, the use of the tropical zodiac in the West was inconsistent - but it cut a more consistent path than the sidereal system. The inconsistent use of astrology in the West was due to a mixture of factors: the rise of the Christian church (which of course did not look fondly on any form of “divination” that steered people away from its teachings - though Jesus in fact mentions astrology kindly in the Bible), and the overtaking of astrology and alchemy by astronomy, due to the Scientific Revolution (4). The scholarship of astrology thus fragmented in different directions, and astrological calculi were picked up and put down by people of varying skill levels at various points in history. (Contrast that inconsistent practice to the Indian approach to astrology, which was maintained regardless of religious and political themes; in the development of Jyotish, Vedic astrology absorbed Western astrology at certain points, but never abandoned their astronomical understanding of the basic fact that the equinoxes move in retrograde motion.) 

To put a finer point on it, you can think of the Western tropical zodiac as a very beautiful, old pocket watch that you might find in an antique store full of collectibles. At various points, people have encountered this curious clock, and decided to start using it again—without winding its hours to account for the time lapsed while it was out of use.

So, let us not misconstrue the “cosmological time lag” of the Western tropical system as a “cultural issue” - or acknowledge it is a scientific issue related to a cultural blindspot on the part of the West. The crisis about whether to align our astrological clocks with the true position of the equinoxes is an issue of incomplete astronomical knowledge in the West at key points in the popularization of astrology. Yet another reason the colonization and trampling of cultures is poor form. You lose massive databases of valuable knowledge! 

That was a lot! Take a break, have a cookie, and come back to read the next part of this post to uncover the second false dichotomy in the “tropical versus sidereal” debate. 

 

1.Powell, Robert. "The Ancient Babylonian Sidereal Zodiac and the Modern Astronomical Zodiac." Accessed Jan. 20, 2025. 

https://www.academia.edu/10266886/The_Ancient_Babylonian_Sidereal_Zodiac_and_the_Modern_Astronomical_Zodiac

2. Bowser, Kenneth. 'An Introduction to Western Sidereal Astrology.' https://www.westernsiderealastrology.com

3. Banherjee, Partho. "Sidereal OR Tropical Zodiac for Indian Astrology Part 2." Accessed Feb. 1, 2025. 

 https://www.astrologyofbharat.org/2019/09/sidereal-or-tropical-zodiac-for-astrology-Part2.html

4. Borealis, Alexey. "History of Astrology: From Its Early Days to the Present." Accessed Feb. 2, 2025.

https://morinus-astrology.com/history-astrology/