The Zodiac: The Origins of Our Solar Calendar

The Zodiac

Yes, the Zodiac.

The word itself creates in our mind a shimmering pop-up of stars in a dark blue sky background painted with purple and pink galactic gas. The Zodiac. All of a sudden, a fast burst of mystery, so fast we can’t even notice it, runs sharply through our veins.

That group of stars that “form” symbolic images up there in the heavens. Constellations, or group of stars named after a particular shape resemblance.

Twelve of them are the constellations that comprise the “Zodiac” (but there are more constellations).

So let’s start with some background.

Ancient men, around the Neolithic (10200-5000 BCE or so), were living a very primal life, as we can possibly imagine. Being stroke by climate and seasonal changes without a proper way to understand them, or prepare for them.

How could they know about changes in their environment? Be prepared for when vegetation died and people died without proper preparation. Or when was the appropriate time to plant crops, harvest and store?  These people didn’t have a clue. But what they had was plenty of time.  As years passed, the observed. And they watched the stars.

The stars. Certain stars were identified precisely just before the dawn of the Sun, lying there up in the horizon. The Sun appeared to be in those stars for some time, and then other group of stars appeared in the same place.

And after continual observation, the same stars re-appeared again after the “year” passed and the seasonal changes occurred, in the right very moment before dawn.  Same happened with the Moon when she was observed to be in these group of stars.

In Ancient Mesopotamia is the origin of the western astrology we know, and the zodiac.

Constellations Zodiac

In order to properly identify the stars, they identified “images” that resembled the group of stars seen just before dawn during different times of the “year”, and the image assigned had to do with the main situations that they experienced during that time, so that it was easier for them to make the “connection” between the constellation and what was happening down here on Earth.

So the zodiac constellations (group of stars) were designated by people to predict changes in early tribes, as a reference point. And because life, nature and religion in those times were strictly connected, the constellations and the astrological phenomena represented a divine symbolism and received a more spiritual/religious/mystical meaning by the people and the cultures. They were viewed as “signs” from the Gods.


The Earth at the very centre of the stars system. In astrology, we work with the geocentric system, since we study the changes on Earth itself (image source unknown)


Sidereal Zodiac

Originally, they used different images and constellation names. But constellations sizes were not the same (it is quite clear that Virgo, for example, is way much bigger that Aries), leading to inaccuracy.

In around 500 BCE the Babylonians (Mesopotamia) established a zodiac* of twelve “signs” of equal size. Each sign was more or less situated in their “respective constellation”. It was an idealised zodiac, attempting to make the divisions of the signs more accurate. In any case, some of these equal signs still overlap over their neighbour constellation.


Hellenistic Astrology

With conquers and expansions, Mesopotamia was taken by the Persians. And taken by the Hellenistic Empire, which also took over Egypt. Traditions intermingled there. Greeks learned from the Babylons (the main city in Mesopotamia). And they also learned about the kind of astrology practised in Egypt. The cultures mixed. This was the beginning of Hellenistic astronomy and astrology.

They became quite proficient in this art. It was clear that there were twelve group of stars, and that the Full Moon also was visible at her fullest one time in each of these twelve signs as the Sun travelled along (a year).

The symbolism started to be associated with the seasonal changes.  There were four main seasonal changes in a solar journey around the earth. Dividing these four into the initial, middle and end stage of a one season made quite sense. The zodiac ended as it follows:

  • four cardinal signs in the positions of the rise of spring (the vernal equinox or Aries), the beginning of summer (Cancer or summer solstice), autumn (the autumnal equinox or Libra) and the beginning of winter (Capricorn or winter solstice);
  • four fixed signs (in the middle of spring, there is Taurus; in the middle of summer, there is Leo; in the middle of autumn, there is Scorpio; and in the middle of winter, there is Aquarius), and
  • four signs in the very end of each season, preparing to mutate into the next season (Gemini mutating from spring to summer, Virgo mutating from summer to autumn, Sagittarius mutating from autumn to winter, and Pisces mutating from winter to spring).


Here (image source unknown) we see the seasonal changes, starting from March 20, spring or Aries; followed by June 21st, summer or Cancer, then September 23rd, autumn or Libra, and December 22nd, winter or Capricorn
Here (image source unknown) we see the Earth in the centre (in astrology we work with the geocentric model, since the Earth is what we are observing), the celestial equator (or Earth’s own rotation axis orbit), the ecliptic (or the apparent path of the Sun and planets “around” Earth), the equinoxes (or the exact points where the celestial equator and the ecliptic meet each other on Aries 0° or spring, and Libra 0° or autumn), the solstices (or the highest and lowest points of the Sun: the longest days or Cancer summer solstice, and the shortest days or Capricorn winter solstice)


It is also important to note that at some point, when the Persians took Mesopotamia, they also became interested in the astrological tradition. And then later when the Arabs conquered Persia, they also became interested in the astrological knowledge. Here the two traditions mixed, giving birth to other new practises and approaches.

Tropical Zodiac

Anyway, at some point, it was understood that the equinoxes were not exactly aligned with their “corresponding” constellations in heavens anymore. They appeared to be moving. The spring/vernal equinox, which once was in the Aries constellation, was now almost in Pisces.

The Ancients were aware of this phenomenon, but there was not a concrete explanation for this until more modern times. This phenomenon is called the Precession of the Equinoxes, caused by the wobble of Earth’s rotation axis moving, due to the gravity pull from the Sun and the Moon.

The constellation zodiac then, was separated from the idealised constellations (which have very different sizes, and it is not easy to delineate their limits). It became fixed and aligned with the equinoxes and solstices points, which are the points linked with the motion of the Sun and Earth, and their relationship marking the seasonal changes. Claudius Ptolemy (100-170 CE) has been a major influence for this.

The circle began at Aries 0°, in the vernal equinox, the rise of spring, and then it was followed by the rest signs.

The zodiac was itself divided into twelve signs, each of 30°, a total of 360° in a solar year calendar (twelve months). These signs are just “parts” in the space surrounding our Earth, where we see the Sun and the planets travelling “around the Earth”. The tropical zodiac is fixed and allows a calculation that is more accurate and precise.


Connection with Indian Astrology

The astrological knowledge was also translated into Indian, and here different traditions also mixed, giving birth to other approaches of the practise of astrology (Vedic Astrology). But in Vedic Astrology, the zodiac used is the constellations zodiac (sidereal). And here it is quite important to note that Vedic Astrology has its own different origin and history, with their original lunar sign zodiac.


Signs or Constellations

Nevertheless, going back to western and Hellenistic Astrology, this zodiac was not “attached” to the constellations anymore.

Here (image source unknown) we see the four quadrants of the four seasons, and its respective sign. Each sign is divided into 30°, for a total of 360° circumference around Earth.

By this time, Aries constellation was aligned with Aries sign, at 0° in the vernal equinox point (rise of spring). So it was all perfect and marvellous.

But they knew it wouldn’t last forever, since it was clear that the “equinoxes” were moving backwards (now we know it is not attributed to the “equinoxes moving”, but to Earth’s rotation axis wobbling)

In this topic, Dane Rudhyar (1985), in The Practice of Astrology states clearly:

The vast majority of astrology devotees (and critics) have not yet comprehended that the zodiac signs have nothing to do with the stars or constellations of today, but instead, they simply represent the twelve phases of cyclic relationship between the Earth and the Sun


This is the tropical zodiac, used in Western Astrology. It is based on the angular relationship of our planet Earth, and our star which gives us life: the Sun. Not in the constellations up there.

With the tropical zodiac, the meaning of the Zodiac signs, their archetypes, their symbolism, their correlation with Earth events and people traits, have nothing to do with the star constellations up there.

Once in a time yes, the stars were used as a reference point, to predict changes. And as time passed, the stars forming the constellations began to be taken as the point of reference for the cosmic symbolism by different traditions and practitioners.

By that time, the constellations coincided (so so) with their corresponding signs, since the equinoxes were aligned with their corresponding cardinal signs.

But the Earth rotation axis has been shifting (due to the Earth Wobble), so the “equinoxes have been moving backwards” (approximately 1° every 72 years) and the constellations are not aligned with the signs anymore.

Our Earth-Sun relationship, which is the core of the tropical zodiac, it is not based upon the constellation stars, but upon the angle of the Sun in respect to the Earth.

In this image (source unknown) we can see clearly Tropical Aries 0° (Vernal/Spring Equinox), by the Pisces constellation


Reinforcing this idea, Alan Leo (1899) in Astrology for All, adds:

The zodiac is one of the most important factors to become thoroughly acquainted with, this being the track, or belt, through which all the planets pass; it is commonly known as the ecliptic, cutting, as it were, the equator at the spot that is called the first point of Aries. The signs of the zodiac should never be confused with the twelve constellations of the same name; at certain periods of the world’s evolution the signs and the constellations corresponded

There are zodiac constellations, and there are zodiac signs. These are not the same.

In modern western astrology, and for the treatment of the soul, personality and events, the tropical zodiac is the most used.

However, there are many practitioners who use the constellations or the sidereal zodiac, particularly in the Vedic or Hindu cosmology system, which is a different system than the one used in the western (inherited from the Babylonians and the Greeks). They work under different approaches and techniques, and both are valid under proper use and interpretation of the symbolism.

Nevertheless, remember that the “images” associated with the constellation designations have been created by men, while the angular relationship between the Sun and our Earth, divided in twelve equal parts (or angles, or zodiac signs) is just there.

An indeed, the zodiac signs kept the constellation names, opening field for confusion. And even more when many astrology column writers talk about “the stars influences”, or “the constellations”, making the public think about constellations instead of signs.


Southern Hemisphere?

Here, one might ask how does astrology work in the southern hemisphere, where seasons are inverted. How can we attribute the meaning of a sign (e.g. Leo) while it is associated with summer and warmth in the northern hemisphere, but in the southern it is cold?

There is not a fixed explanation on why the western astrology system, which originated from a northern hemisphere base, still functions for people in the southern. I dare to say, that the zodiac sign traits are linked to the angle they form by the Earth-Sun relationship.



There is so much that we still don’t know. In the present time we can read a lot of information out there, we can listen to different points of views, see different approaches within the practise of astrology, by different cultures.

In the end, astrology works as a frame of reference to interpret symbolism, which is meaningful to us. From history, discoveries and available literature, we can know more about how it all began. But we will never be 100% certain of how it actually began and developed. We just latch to what makes more sense to us and works best for us.

What I have presented here was based upon my own personal questioning about the matter. It is a compilation of information that made sense to me, after reading material available, books, and after having directly contacted senior experienced astrologers.  In today’s practise, both sidereal astrologers and tropical astrologers have their own reasons and attributions to their practise. But this article was to bring more light to the zodiac, seasons and constellations.

And as we can see, the tradition of astrology has been a dance of culture and traditions for thousands of years! Influenced and influencing cultures and traditions simultaneously. Having its rises and its falls. Being banned, destroyed and reborn. Being in the shadows, but still alive. Being repudiated, but still reinforced. And despite of all these events, we still have this knowledge. And it is just amazing to be participate of this tradition today.

In summary, if you go out there with your Google Sky app (of course, this means now in the time this article was posted), search out for the Sun, you will find that the Sun is actually in Capricorn constellation. But for tropical astrologers, the Sun is in Aquarius, the zodiac sign corresponding to this time of the solar year. And this would apply to any time. You will find the Sun in one constellation, while it might actually be in the next zodiac sign.

Sun in Capricorn constellation (image from Cosmic Watch app)
Same time, but Sun in Aquarius sign (image from Cosmic Watch app)




Hellenistic Astrology: The Study of Fate and Fortune by Chris Brennan (2017)

A Brief History of Ancient Astrology by Roger Beck (2007)

The Practice of Astrology by Dane Rudhyar (1985)

Astrology for All by Alan Leo (1899)

Toward an Understanding of the Two Zodiacs by Glenn Perry




*The Babylonian MUL.APIN




Note: In order to make things easier, I had to search some images in the internet so that you could understand better. Unfortunately, with exception of the last two and the first featuring image, I don’t know the original source of the other images, but they work quite good to reinforce the explanations with visual objects. Apologies.


Featuring Art: Woodcut of the celestial sphere by Erhard Schön. Source from Adam McLean