Two weeks ago, I outlined what I believed to be a very “brief” overview of the history of astrology. I gave the overall gist of the practice, not really getting into its complex inner workings. (For that I highly recommend Chris Brennan’s book, Hellenistic Astrology: The Study of Fate and Fortune, and his various websites that I referenced heavily throughout the piece.) Because of that I glossed over one very important development that has had rippling effects that can still be felt up until this day: the presence of two distinct Zodiac.
During the Mesopotamians’ time, they simplified 18 (sometimes 17) uneven physical constellations (today we call the standardized 13 ones the “constellational Zodiac”) into 12 Zodiacal “signs” that still repped their constellational names such as Aries, Taurus, etc. But why did they do this?
One simple answer is that 12 is the easiest way to divide up a circle. Since the Earth revolves around the Sun in an elliptical, or slightly oval-shaped, fashion, the ecliptic plane, the 8° path the Sun (and other planets) travels through in the sky from Earth, as a result is also elliptical. An oval, like a circle, has 360° in it. Ergo, if you want to divide it equally, you would have 12 parts with 30° within them.
A more complicated reason is linked to how calendars are formed. There are 365.25 days in a solar year and the Moon goes through twelve cycles throughout this solar year. It takes around 27 or 28 days for the Moon to revolve around the Earth (a sidereal month), but around every 29 or 30 days for the Sun and Moon to meet up and for the Moon to go through all of its phases (a synodic month). In 12 lunar (synodic) months, we get around 354.36 days in a lunar year. Hence, we tend to have calendars that consist of around 360ish days divided into 12 months with around 30 days in each one.
Some argue that the Mesopotamians standardizing the constellational Zodiac into 12 signs precedes this calendrical convention, but in either case, the vernal equinox, which occurs around March 20/21, was always close to the beginning of the Babylonian new year. Therefore, the first month of the year began when the Sun was in the constellation now known as Aries. Constellation is emphasized here because the Babylonians developed the idealized 12 sign Zodiac from their sidereal or (fixed) star positions. That is to say, the sidereal Zodiac uses the approximate location of the physical constellations as a reference point, and there was two ways they did this.
One system states that the position of the Sun at the time of the vernal equinox was defined as 10° Aries, and in another as 8° Aries. This is important because the ancients did not know that the equinoxes slowly moved due to precession. Consequently, they did not know over the next 2,000 years that the Sun would slowly move backwards through the constellations. In other words, the ancients did not know that today in 2020, the Sun rising on the horizon during the vernal equinox would be in the physical constellation of Pisces, not Aries.
But why is this occurring? To answer that we need to get into some basic astronomy.
The vernal equinox is the point where the ecliptic and celestial equator meet. This point is where day and night are perfectly equal at all latitudes and where the Sun is directly overhead at the equator around noontime, either moving from south to north or north to south. This occurs twice a year, once in the spring (the vernal equinox) in the Northern hemisphere around March 20/21 and in the fall in the Northern hemisphere around September 22/23 (the autumnal equinox).
However, since the Earth’s axis tilts around 23.4°, we also have solstices, or when the Earth’s tilt (obliquity) is at its maximum. The first one occurs around June 20/21 where the North Pole is pointed towards the Sun. This day is the longest day of the year and marks the beginning of summer for the Northern hemisphere (summer solstice) and winter for the Southern hemisphere. The last solstice occurs around December 21/22 where the North Pole is tilted away from the Sun. This is the shortest day of the year and winter begins in the Northern hemisphere (winter solstice) and summer for the Southern hemisphere.
Because the Earth wobbles along its axis, the orientation of the poles changes in relation to the stars over time. And as Earth’s axial rotation moves, the equinoxes move as well.
The precession of the equinoxes is a phenomenon where the wobbling effect causes the Earth’s axis to move about 50.3 seconds of arc per year or 1° every 71.6 years. One cycle takes around 25,772 years to complete. Currently, the North Pole is aligned with the star Polaris which was not the case 3,000 years ago. In 14,000 CE the North Pole will be aligned with Vega, not Polaris. In terms of astrology, this means where the Sun is during each equinox and solstice in relation to the constellational Zodiac has also changed over time. As was mentioned above, today when one looks east at the rising Sun, it is in the constellation of Pisces, not Aries as it was for the ancient Mesopotamians.
An interesting tangent I would like to add is that every 2,100 years (around 30° in the ecliptic) into this 25,772 precession cycle marks the beginning of a new Zodiacal Age. These so-called Astrological Ages is a very new invention, only appearing in the 19th century and was conceptualized and pushed by the Theosophists. Like with other Theosophist ideas, this invention became associated and popular with the New Age movement of the 1960s and ‘70s. With Pisces on the horizon during the vernal equinox, we are said to have been in the Age of Pisces for a while and should be heading into the Age of Aquarius sometime soon or in the distance future in 2356 or 2600.
But let us get back on track and refocus on the purpose of this article: to explain the presence of two Zodiac. The Zodiac that uses the stars in space as a reference point is today called the sidereal Zodiac. The Zodiac that uses the vernal equinox as a reference point is called the tropical Zodiac. This may be a bit confusing considering the ancient Mesopotamians seemed to have used the vernal equinox to define the Zodiac as well but let me break down these modern differences for you.
The physical constellations are clusters of stars that have been grouped together to create an image of an animal, idea, or person. The constellations are unequal and located in space. The Babylonians charted out 17-18 in the ecliptic, which included the 12 Zodiacal ones we are all familiar with but with Pisces sometimes split into 3 (“The Tails,” “The Great Swallow” (sometimes these two constellations were combined into 1), and “The Goddess Anunitu”) and the constellations of Pleiades, Orion, Perseus, and Auriga. In 1928 astronomers in the International Astronomical Union (IAU) made a list of 88 official constellations (there were 48 during the Babylonians’ time, including the Zodiacal ones). In the ecliptic there are 13 constellations, the 12 Zodiacal ones and Ophiuchus which is sandwiched in between Scorpio and Sagittarius.
The sidereal Zodiac refers to the simplified, equal sized signs that are representative of the physical constellations. The Sun in this system stays up to 30 days or 1 month in each sign. The beginning of this Zodiac depends on where in space the 0° of Aries is determined. During the Mesopotamians’ time, they chose the vernal equinox point fixed at either 8° or 10° of the Aries constellation to begin the Zodiac. This reference point is no longer used today. Because modern astrologers are aware of precession and its effects on charting the movement of the planets, they must be cognizant of the fact that their numbers can be off. Therefore, they must pick a star or a point close to a star to mark 0° of Aries.
Spica is a popular choice. It is a very bright star that is 2° south of the ecliptic. It lies within the physical Zodiacal constellations of Virgo and Libra. Using Spica as a reference point, you calculate 180° across to get 0° of Aries. You calculate backwards because it is hard to physically see the constellations and the Sun at the same time because the Sun’s light blocks out other objects in the sky. Therefore, you would need to find a star opposite it to calculate which constellation the Sun is in. But even with the common choice of Spica you still have problems.
Western sidereal astrologers who invoke Cyril Fagan and Donald A. Bradley’s calculations positions Spica at 29°06 of Virgo. However, Indian astrologers who use Nirmala Chandra Lahiri’s measurements argue that Spica is at 0° Libra. As a result, sidereal methods will produce slightly varying astrological charts even if they are using the same star. This is again due to precession because where the Earth is in relation to the stars changes over time. Vedic astrologers place Spica at 0° Libra because they are viewing the star where it was in 285 CE (or 290 CE) when the sidereal and tropical Zodiac were said to be aligned or in 499 CE when the Suryasiddhanta was written. Fagan/Bradley meanwhile are looking at Spica where it was at in 221 CE.
Differences like these do not end with just these two popular choices as there are numerous stars or points close to specific fixed stars within the 12 Zodiacal constellations that astrologers can pick and choose from. To make matters more complicated, to even get these measurements one has to take note of the tropical positions of these stars because “sidereal ephemerides are derived from tropical ephemerides by subtracting a certain difference value from the tropical positions of the planets.”
In other words, since the tropical Zodiac has been favored by Western astrologers for over 2,000 years, in order to calculate the sidereal positions of the planets, you must account for the degrees, minutes, and seconds of separation between a planet’s tropical and sidereal position first. This difference is called the ayanamsha. Therefore, sidereal Zodiacs are named after the astrologer(s) who did the calculations followed by the term ayanamsha (e.g., Fagan/Bradley ayanamsha, Lahiri ayanamsha, etc.). Ayanamshas change with the years because of precession. So, for example, the Fagan/Bradley ayanamsha placed Spica at 24°44’12’’ of Virgo in 2000 and 24°02’28’’ in 1950. The Lahiri ayanamsha, meanwhile, had Spica at 23°51’11’’ of Virgo in 2000 and 23°09’27’’ in 1950.
But why did Western astrologers disregard the sidereal positions of the Zodiac in favor of the tropical ones in the first place? Well, we can thank Claudius Ptolemy for that.
Ptolemy’s works shaped the future of astrology and astronomy for centuries
Apparently, Ptolemy is one of the first major Hellenistic astrologers who adopted the tropical Zodiac. Within this system, the 12 Zodiacal signs are divorced from the physical constellations and are instead tied to the seasons where the signs are divided into 30° segments along the equinoxes and solstices. The vernal or spring equinox marks 0° of Aries, the summer solstice begins Cancer, the autumnal or fall equinox starts the Sun’s ingress into Libra, and finally the winter solstice marks 0° of Capricorn. The rest of the signs fill in the gaps of this cross in order from Aries.
Because the signs are linked to the seasons in the tropical Zodiac, Ptolemy argued that the primary characteristics of the 12 signs came from their tropical rather than sidereal positions. That is to say, since the tropical Zodiac aligns with the seasons, then signs that occur at the beginning of a season are action-oriented and leaders (cardinal signs), signs that occur in the middle of the season are more stable and plodding (fixed signs), and finally signs that occur towards the end of one season and the beginning of another are more flexible and go-with-the-flow (mutable signs). Today, we call these specific seasonal qualities a sign’s modality or quadruplicity. But whether or not the earlier Mesopotamian (and/or Egyptian) astrologers derived the qualities of the signs from the seasons, fixed stars, or both is hard to say.
Regardless, Ptolemy’s assertions were actually not popular during his time, and many astrologers seemed to have continued on using some sort of sidereal Zodiac unbothered. However, by around 350 CE, there was a shift and suddenly the tropical Zodiac as spearheaded by Ptolemy became more widely adopted and accepted. The tropical Zodiac has since the late Hellenistic period dominated what we now call Western astrology into the present. Today, the tropical and sidereal systems are around 24° off from one another where you subtract 24° from the tropical position of a planet in order to get its sidereal position due to precession.
Although apparently the ancient Egyptians were aware of the precession of the equinoxes but not the Mesopotamians, Greek astrologer Hipparchus of Nicaea/Rhodes (190 BCE ~ 120 BCE) is credited as the first person to “discover” this phenomenon in the 2nd century BCE.
Hipparchus was jotting down the locations of the stars and comparing his measurements to those done by astrologer Timocharis who lived one and a half centuries before his time. But Hipparchus noticed his numbers were off. Spica had been 8° to the west of the autumnal equinox in Timocharis’s time, but to him Spica was 6° to the west of the autumnal point. The star had moved, or worse, the Earth was not in fact the center of the universe, but the Sun!
Although this would have been revolutionary during Hipparchus’s time, historians seem split on whether or not Hipparchus entirely understood what he was observing while others assert that he knew for sure that the equinoxes were moving. Some even argue further that he converted to the tropical Zodiac soon after this event.
In either case, however, Ptolemy (100 ~ 178 CE) fully embracing the tropical Zodiac shifted the tides of how Western astrology was practiced forever. As was noted in my post on the history of astrology, some of his works that were preserved both in Arabic and Greek were immensely influential and foundational to the resurgence of astrology in Europe during the Middle Ages onwards. His Almagest and Tetrabiblos were very popular. In the Almagest, Ptolemy explains his rationale and calculations for the tropical Zodiac while in the Tetrabiblos he argues for the usage of the tropical Zodiac at length:
But it is indeed reasonable to start the twelfth-parts and the boundaries from the tropical and equipartite points—that we will not omit, as it happens to be worth dwelling over. This is both because the writers in a certain fashion make this clear, and especially because we see from the previous demonstrations that the natures and powers and [planetary] affiliations of the twelfth-parts and boundaries derive their cause from the tropical and equipartite origins and not from any other starting points. For, if other starting points are assumed, we will either be forced no longer to use the natures of the zodiacal signs in prognostication, or else, if we use them, we will be forced to make mistakes because of the overlappings and separations of the intervals that secure the powers in them. (Brennan, 2017, pp. 219)
What is a bit ironic about this statement is that the two Zodiac were roughly aligned during Ptolemy’s time (200 CE). Consequently, it is not hard to find some Hellenistic astrologers who used both the sidereal and tropical Zodiac to delineate. For example, astrologer Vettius Valens (120 ~ 175 CE) would invoke both the season and fixed star(s) associated with a sign to find meaning within a birth chart reading. This continued on with Arabic astrologers well into the 8th and 9th centuries CE.
Because of the numerous bust and boom cycles of astrology post the Hellenistic period, however, this flirting of both systems seems rather inconsequential now as the majority of Western astrologers today predominately use the tropical Zodiac while Indian astrologers predominately use the sidereal positions. There is a popular theory pushed by a Western scholar as to why this division exists but it seems highly controversial to Indian astrologers so we will not go in depth about it here, but you can read about it here. What we will go into a little depth in is how sidereal astrology was revived in the West to mixed results.
Irish astrologer Cyril Fagan (1870 – 1970) is credited as the man who reintroduced sidereal astrology to the West. He actually studied astrology from the tropical positions from 1916 up until 1944 when he switched. In the 1940s Fagan began studying translated ancient Babylonian astrological/astronomical texts and realized that they used the sidereal positions (or the physical Zodiacal constellations), not the tropical positions as more commonly practiced by the Greeks. This compelled Fagan to do his own research comparing tropical and sidereal solar and lunar returns and he noticed that they yielded different results. For instance, in a solar return chart, the difference in time can amount to a whole day when the subject is 72.
Fagan then argued that because of these differences, Western astrologers should return to how the Babylonians practiced the art by using the stars rather than the equinoxes. (What is interesting, however, is that he also seemed to take cues from Indian astrology in his early transition.) Fagan went on to write numerous books and columns on sidereal Western astrology. One influential book was Zodiacs Old and New (1950) where he placed Spica at 29° Virgo based on his research into the origins of the exaltation degrees (hypsomata). He originally called this sidereal ayanamsha the Hypsomatic ayanamsha.
Donald A. Bradley (1925 – 1974) is another Western astrologer who is often credited alongside Fagan for reintroducing sidereal astrology to the West. He was the research director for the Llewellyn Foundation for Astrological Research, and like Fagan, he was once a proponent of the tropical Zodiac but soon switched over to the sidereal Zodiac during the ‘40s as well. One of his big research projects was on 2,492 clergymen that showed that the 12 Zodiacal signs were allegedly not where supporters of the tropical positions claimed they were. This paper was also published in 1950, and Bradley was very aware of Fagan and his work.
In fact, Bradley championed for Fagan but also corrected his work. From his own research into the hundreds of sidereal lunar and solar ingresses into the cardinal signs, Bradley argued that Spica was actually at 29°06 Virgo in 1957. Within this ayanamsha (the Synetic Vernal Point [SVP]) he maintained that the stars of Aldebaran and Antares were located at 15° of Taurus and Scorpio respectively as well.
Today, sidereal Western astrologers combine the ayanamshas of both of these astrologers to create what is now called the Fagan/Bradley ayanamsha. This is the oldest Western sidereal Zodiac and is said to be the closest to the Babylonian rendering. As was mentioned near the beginning of this post, there are numerous ayanamshas, some using the same exact stars but positioned in different constellational Zodiacs. Spica (or Citrā), for example is used by Indian astrologers too. But the Lahiri ayanamsha says Spica is at 0° Libra. So, what does this mean for the sidereal Zodiac?
Unfortunately, those who support the sidereal positions often claim that, unlike the tropical positions, the stars do not move, or move so slowly that it doesn’t matter as the equinoxes objectively move more. Because of this, the sidereal Zodiac is more “accurate” as it still references the physical constellations in some way. As we have seen throughout this post and my previous one, these assertions of accuracy are a bit subjective and biased depending on which school of thought you follow and which techniques you utilize. The constellations themselves have changed over thousands of years. In fact, the Mesopotamians reducing their 17-18 constellations to 12 idealized ones in itself presents issues of accuracy. Are there 17-18 constellations (ancient) or 13 (modern)? Should there consequently be anywhere from 13 to 18 Zodiacal signs? Which Zodiac should bend to the reality that the constellations and Earth’s relation to them have shifted considerably over time?
These are questions that even the most highly esteemed astrologers from all different backgrounds and practices cannot seem to reconcile or answer completely. In my opinion, handwringing over accuracy is a bit of a moot point as I approach the metaphysics from a place of self-discovery and inherent changeability. Subjects like astrology are vast and ever intricate and complex. No one culture practices it one way, and within one specific culture and subfield, there is a myriad of ways to interpret and practice. Therefore, just because one astrologer says X does not invalidate another saying Y. Both can and do exist in the same space regardless of how I personally feel. From this framework, arguments over accuracy and resonance are circular and needless, in my opinion at least, because I already accept, if not embrace, the versatility of astrology and other occult sciences.
With that said, tell me how you feel about the two Zodiac. Are you a proponent of the tropical or sidereal positions? Or do you use both? Or are you a neo-Vedic, typically a Western person who uses the tropical Zodiac within the Indian/Vedic astrological framework? Do you use techniques from either Zodiac such as fixed stars for the tropical Zodiac or time lords for the sidereal Zodiac? Let me know in the comment section below.
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