The tropical zodiac is constructed from the locations of the equinox and solstice points. For example, in the tropical zodiac, the sign of Aries begins at the vernal equinox which initiates spring in the northern hemisphere. Each sign is then constructed by thirty-degree increments starting from the vernal/spring equinox. The other three cardinal signs align with the solstices and equinoxes. The tropical sign of Cancer begins at the summer solstice, the tropical sign of Libra begins at the autumnal equinox, and the tropical sign of Capricorn begins at the winter solstice.
The equinox and solstice points gradually shift backward through the constellational zodiac due to a phenomenon known as the precession of the equinoxes. Put simply, this precession results from the Earth's wobble along its axis as it orbits the Sun. Thus, in the tropical system, the first degree of Aries shifts backward through the constellations so that today it falls in the constellation of Pisces instead of Aries. This backward shift occurs at a rate of one degree roughly every 72 years. The symbolism of the tropical zodiac draws heavily upon the seasonal rhythm rather than the ecliptic constellations despite assimilating their names and images.
During the Hellenistic era, however, the tropical and sidereal zodiacs roughly corresponded with one another, and their symbolism influenced the meaning of the signs in each system (Brennan, 2017, 217). The discovery of precession did not occur until around the second century BCE. It even then was not widely recognized by astrologers for several centuries after that (Jones, 1989, 29). It took time for the tropical zodiac to gain more widespread use among astrologers, but once it did, it solved a problem that precession eventually brought about: the gradual movement of the constellations and sidereal signs relative to the equinoxes and solstices.
There is still debate in both academic and astrological communities over the historical development and usage of these systems in the ancient world. The Hellenistic tradition of astrology that developed in Greece and later in the Roman Empire evolved more complexity to which modern western astrology is heavily based. The correspondence, or rulership, of certain planets and tropical zodiac signs, developed out of the Hellenistic astrological tradition and it works strictly within the framework of the tropical zodiac.
The seasonal symbolism inherent to the tropical zodiac is obvious. The initiatory and catalyzing qualities of cardinal signs Aries, Cancer, Libra, and Capricorn emerge from their initiation of a new season. The stabilizing qualities of fixed signs Taurus, Leo, Scorpio, and Aquarius result from their static position between seasons. And the association of versatility and instability with the mutable signs, Gemini, Virgo, Sagittarius, and Pisces are related to their transitional position from one season to the next.
The origin of the tropical zodiac and its deviation from the constellations is pretty clear. The zodiac of modern western astrology is, for the most part, starless, with the exception of the Sun and the fixed stars that are occasionally used. Of course, the tropical signs are transposed over the stars and constellations along the ecliptic, and thus everyone's tropical Sun sign is placed among them. However, the meaning of your tropical Sun sign stems from the meaning derived from the tropical zodiac and its complex interaction with seasonal symbolism, the sidereal zodiac, and the names derived from the constellations.
Which Zodiac is Correct?
The confusion over the three zodiacs and their association with astrology often spark debate in the general public, scientific and academic communities, and among astrologers themselves. It's important to realize that the premise of astrology, that celestial events correlate with Earth-based events is agreed upon no matter what branch of astrology a person comes. It doesn't matter which zodiac system one uses, the planets or other placements are typically the same. One exception to this is when using a heliocentric (Sun-centered) as opposed to the geocentric (Earth-centered) model. There are valid reasons for using the geocentric model in astrology (since astrology uses perspective as a metaphor), but that is a discussion beyond the scope of this article.
From a geocentric perspective, when a planet appears to turn retrograde, an eclipse occurs, or several planets conjoin in the sky, they do so in either zodiac system in the same place in the sky. The difference is in the naming or designation of that portion of the sky. The Sun signs that most people refer to in western society draw their symbolism from the tropical zodiac. The meaning given to those signs represents the intersection of seasonal symbolism from the northern latitudes as well as the system of rulerships born out the Hellenistic tradition of astrology.
For example, in the western, tropical system, the planet Saturn has rulership of Capricorn and Aquarius, and that planet is said to be empowered in being in those signs. Saturn's relationship to other planets or its interaction with the horizon in a chart is the same in either a sidereal or tropical zodiac. The method of assessing the strength and weakness of certain planets based on the placement of planets or objects in a particular zodiac sign differs between the tropical and sidereal.
Some astrologers subscribe to the fundamentalist view that one zodiac is more correct or superior to another. There are proponents of the sidereal zodiac who feel that because the sidereal zodiac aligns more closely with the constellations, it's more aligned with astrology's original foundations. Yet, while the sidereal signs do roughly correspond to the constellations, they don't precisely because sidereal signs are still divided by precise thirty-degree increments while the constellations are not. In the sidereal zodiac, half of Libra falls in the constellation of Virgo, and portions of other signs overlap with more than one constellation.
As a western astrologer, I use the tropical zodiac, and I find that it works within the context of that system. I don't believe the tropical zodiac to be superior or more correct than sidereal, or even the constellational zodiac. The zodiac is simply a way of placing celestial objects in specific positions and tracking their relationships and movements through time. Each zodiac, like the different house systems, reflects different ways of looking at essentially the same thing. For me, the differences between various branches of astrology reflect different perspectives and neither one is more superior or more valid than another.
Even within the context of the tropical zodiac, there is wide variation in the application of that information. A birth chart can be used to assess topical life events, personality characteristics, psychological disposition, or even the purpose or destiny a person is meant to carry out. There are also significant differences between a chart cast for a person, event, or object. Astrology is all about perspective, and I think that diversity within and between cultures should be embraced.
The idea that a system of knowledge should be homogenized and static suggests that there is only one way to understand reality. If astrology can teach us anything, it's that the truth can be understood from multiple points of view and there are many ways to arrive at it. An individual's horoscope is not a proclamation of a static and unchanging fate and destiny, and even if such a thing exists, I don't believe astrology can give a definitive picture of it.
As a tool of divination, astrology operates as an oracle that works on the basis of acausal or synchronistic principles. No matter which zodiac or paradigm an astrologer (or anyone) uses to interpret a chart, there will be wide variation in the encoded information. And there will be variation in how that information is decoded by the person receiving the information. In my perspective, astrology's goal is not to espouse some strict view of who a person is or might become, but to inspire in them the ability to engage in their lives co-creatively and to realize that their lives are a part of a much vaster and interconnected whole.
Sources
Brennan, Chris. Hellenistic Astrology: The Study of Fate and Fortune. Denver: Amor Fati Publications, 2017.
Holden, James Herschel. A History of Horoscopic Astrology: From the Babylonian Period to the Modern Age. Tempe: American Federation of Astrologers, 1996.
Jones, Prudence. “Celestial and Terrestrial Orientation: The Origins of House Division in Ancient Cosmology.” In: History and Astrology: Clio and Urania Confer, ed. Annabella Kitson. London: Unwin, 1989.
Lash, John. Quest for the Zodiac: The Cosmic Code Beyond Astrology. Loughborough: Thoth Publications, 1999.
Rochberg-Halton, Francesca. Aspects of Babylonian Celestial Divination: The Lunar Eclipse Tablets of Enuma Anu Enlil. Horn: Berger, 1988.
Rochberg, Francesca. The Heavenly Writing: Divination, Horoscopy, and Astronomy in Mesopotamian Culture. Cambridge: Cambridge University Press, 2004.
