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, of course, many more! You know the popular Orion and his belt).

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. These guys were stroke by climate and seasonal changes without a proper way to understand them, or prepare for them.

How could they know when winter was coming? Vegetation died and people died without proper protection. Or when the heat of the summer was coming? 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, time passed, 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 order to properly identify the stars, these guys created “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.

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


The seasonal changes were the most important issue to measure. For example, Glenn Perry in his article Toward an Understanding of the Two Zodiacs mentions that Scorpio, which symbolises death (and rebirth!), was a way to announce early to the tribes that death (winter),  was coming, destroying vegetation and life. Or Leo, which symbolises vitality and colours, was in the middle of summer.

Originally, they tried with different images and constellation names. But it was just in 500 BCE that the Babylonians established a twelve constellation zodiac. Of course, it made sense. 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

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).

Each season started by the very centre of the constellation observed in the sky. However, constellations sizes were not the same (it is quite clear that Virgo, for example, is way much bigger that Aries), so it can be said that measuring the times was not precise.

Here (image source unknown) we see the Earth in the centre (in astrology we work with a geocentric chart, since 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)

So the zodiac constellations were created and used to measure seasonal changes in early tribes.

And it all was great. People could prepare for seasonal changes, monuments were built to honour them, festivities were celebrated (Easter or Ostara or Eostre, and the Harvest Full Moon closest to the autumn equinox). Mythology surrounding the stars started. The practise of observing and measuring the skies became a job in ancient Babylonia. Celestial bodies became deities, and predictions started to account, in the name of the stars. 

With conquers and expansions, the Greeks learned from the Babylons. This was the beginning of Hellenic astronomy and astrology.

And then it was discovered in 134 BCE, by a Greek astronomer called Hipparchus, that the equinoxes were not exactly aligned with their “corresponding” constellations in heavens anymore. They were moving. The spring/vernal equinox, which once was in the middle of Aries constellation, was now almost at 0° Aries constellation, moving backwards towards Pisces!

There was, of course, no explanation for this until 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.

Later on, around 100-170 ACE, Greek Ptolemy established a fixed zodiac, aligned with the real equinoxes and solstices points, marking the year calendar of the Sun, and the four seasons.

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

In order to make the calculation accurate and precise, the zodiac was itself divided into twelve signs, each of 30°, a total of 360° in a solar year calendar (twelve months).

But this zodiac, was not attached to the constellations anymore, since for their purposes and their eventual discoveries, the constellations had nothing to do with the seasons and changes on Earth.

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!)

And, if we talk about astrological ages, this event took place during the Aries Age (around 2260-100 BCE). Translated into symbolism: Aries is the rise of spring, the rise of life, the rise of knowledge, consciousness. Therefore, this events marks the beginning of the cycle, the beginning of true astrology.

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

An indeed, the zodiac signs kept the constellation names, opening field for confusion.

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

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 measure the seasonal changes. 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.

And finally, once it was discovered that it was not the stars, but the angle of the Sun in respect with the Earth the real agent causing changes on Earth events and people, constellations had no use anymore in astrology.

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 and it’s proven to be effective and accurate.

However, there are many practitioners who use the constellations (sidereal astrology), 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.

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?

In astrology, indeed, a person from the southern hemisphere will reflect Leo traits, even though it is cold.

There is not a fixed explanation on why the western astrology system, which originated from a northern hemisphere base, still functions perfectly for people in the southern.

I dare to say, that the zodiac sign traits are intrinsically linked to the angle they form by the Earth-Sun relationship. In addition, from the vernal equinox in Aries, the Sun appears to be rising over the ecliptic (regardless of the hemisphere), so the traits will apply to both hemispheres, since it is not the season which determines, but the angle.

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 astrologers, the Sun is in Aquarius, the zodiac sign corresponding to this time of the solar year.

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


To continue the educational posts, read The Personal Signs: Aries, Taurus, Gemini and Cancer.


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


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.

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