3. The Origins of Astrology

Years ago, I once worked with a fellow who professed, in all seriousness, to “believe in” astrology. He had studied it, and claimed that he used to teach it – though I fail to see how it can even be regarded as a subject to be studied or taught! You may think that having someone in a workplace who believes in astrology isn’t anything unusual – but I work in an industry – software engineering – which depends very much on the application of logic and rational thought, and in which most people are educated to degree level, and by necessity, scientifically and mathematically literate. Go figure.
As you can imagine, I had a few quite heated “debates” with this fellow. I once told him that “believing in astrology makes as much sense as believing in fairies at the bottom of your garden!” For all its glibness, this comparison is actually a very valid one, as both of those beliefs are derived from ancient and centuries-obsolete world views.
While the concept of fairies is today nothing more than a children’s fantasy, I would suggest that it’s a distorted remnant of an ancient “nature-worshipping” culture, in which everything in nature was believed to have “spirits”. Similarly, astrology is a hangover from the archaic belief that the Earth was the centre of the Universe, and had been created solely for the benefit of humans.

3.1. The geocentric world view

For most of human history, the Earth was thought to be the centre of “creation”, and stationary, with the Sun, Moon, planets and stars revolving around it. The world was thought to have been created by God or gods, solely for the benefit of Man. The Sun, Moon and planets either were the gods, or were signs, symbols or representatives of the gods.
Such ideas originated thousands of years ago, when people lacked any of the kind of knowledge which we take for granted in the modern world. People have always had a desire to explain and understand the world around them; before the development of science, they had to try to do so in other ways. They couldn’t understand how the world came into being, so they imagined it to have been created by some kind of beings who were far superior to themselves – in other words, gods or deities.
Natural phenomena, such as the weather, were thought to be the work of the gods, and even an indication of their mood; for example, violent and frightening phenomena, such as thunderstorms, meant that the gods were angry. Over time, belief systems evolved, in which the gods were assumed to involve themselves in every aspect of human affairs, and each god or goddess had specific responsibilities. In many cultures, the Sun, Moon and planets came to be associated with particular gods and goddesses.
The first attempts at what we might call a “scientific” explanation of the Universe occurred in the Mediterranean region, and particularly Greece, around 2500 years ago. The Greek philosophers were the first to realise that nature could be explained without attributing everything to gods and magic; they invented what we now call the scientific method, making deductions from observation and experiment. For example, they deduced that the Earth was spherical, by observing its shadow during lunar eclipses, and Eratosthenes calculated its circumference with remarkable accuracy, simply by comparing the position of the Sun in the sky, as seen from different places at the same time.
Most of the Greeks still assumed the Earth to be the centre of the Universe. Aristarchus of Samos actually proposed that the Earth orbits the Sun in 280 BC, but few people took the idea seriously. Ptolemy, in the First Century AD, developed a model of the Universe, which was quite sophisticated, despite being completely wrong! The Earth was a stationary sphere at its centre, and all celestial bodies were attached to concentric crystal spheres, which revolved around it at different rates. The seven known “planets” – the Sun and Moon were regarded as “planets”, while the Earth obviously was not – each had their own spheres, while the outermost sphere held all the “fixed” stars. ( The planets were initially called “wandering stars”, as they move with respect to the “fixed” ones; the word “planet” comes from the Greek for “wanderer”. ) The spheres were turned by an unspecified “Prime Mover” – which Christians would later equate with God.
There was an obvious problem with this model; the planets sometimes reversed their direction of motion! Ptolemy explained this by proposing that they moved in smaller circles, called epicycles, superimposed on their main circular motion.
Following the end of the classical Greek civilisation, scientific progress came to a halt, and in many respects, went backwards. The early Christian church suppressed all scientific enquiry, and destroyed the great Library of Alexandria, such that much of the work of the Greek philosophers was lost for ever. Europe descended into the Dark Ages.
Ptolemy’s cosmology, together with the equally mistaken physics of Aristotle, was turned into religious dogma, which no-one dared question. It remained the accepted model of the Universe, throughout the Mediterranean, the Middle East and Europe, for the next 1500 years.

3.2. Patterns in the sky

I said earlier that astronomy is the oldest of the sciences; in fact, it’s almost as old as civilisation itself, and there were practical reasons why many ancient cultures developed it. Almost every early civilisation realised that the motions of celestial objects could be correlated with the changing of the seasons on Earth. The Sun travelled around the sky, with respect to the background stars, during the course of a year, and its height in the sky at midday varied with the seasons. At night, different patterns of stars came into view at different times of the year, again in a repeating annual cycle. So people learned to use the sky as a calendar; for example, the appearance of particular patterns of stars in the night sky indicated when they needed to plant their crops, and when to harvest them. Many of the religious myths of early civilisations, such as the Egyptians, were in fact fables to describe the annual motions of celestial bodies, and many prehistoric stone circles, such as Stonehenge, are believed to have been built for astronomical and calendrical purposes. And when people began to sail the seas, they learned to use the stars for navigation.
To aid in recognising the stars which appeared in different seasons, people grouped them into patterns, as children “join the dots” in puzzle books. Today, we call these patterns constellations. Many cultures invented their own sets of constellations; those with which we are familiar in the western world originated in the Mediterranean region, and had deep significance within the religions and mythology of various cultures. Of the constellations which astronomers recognise today – they are still used, simply as a convenient way of navigating around the sky, and describing the positions of astronomical objects – there are 48 “traditional” ones, which were known to the classical Greeks and Egyptians, and were “standardised” by Ptolemy in the First Century AD – but many of them are believed to have originated much earlier. ( There are a further 40 in use today, which are modern inventions, dating from the Seventeenth and Eighteenth Centuries. )
With a handful of exceptions, most of the traditional constellations bear little or no resemblance to the people, animals or objects after which they are named. It’s believed that to the people who invented them, the names were more important than the actual patterns; the patterns were named after characters and creatures from their folklore or religious myths, so the sky became a kind of pictorial story book.
Twelve of the constellations – those which make up the so-called Zodiac ( the word comes from the Greek for “circle of animals”, though only seven of them represent animals ) – are of particular significance, as they lie along the apparent path of the Sun, Moon and planets around the sky. The astrological “signs of the Zodiac” share the names of these constellations, and originally coincided with them in the sky – but they no longer do, as I’ll explain in Section 5.

3.3. The rise of astrology

Exactly when and how astrology began is lost in the mists of time – but the familiar western version is believed to have originated around 2500 years ago, again in the Mediterranean region. ( Ironically, just about the same time as the Greeks were inventing real science! ) There are many paintings and carvings in Egyptian tombs, dating from around 2000 years ago, which depict the familiar symbols of the Zodiac “signs” – showing that the system was already well-established by that time. So its origins probably date back a few more centuries. There is a very good reason why it could not have originated much earlier than about 1000 BC – which I’ll explain in Section 5. However, the constellations of the Zodiac, with which the astrological “signs” were originally associated, are thought to be very much older. There is a very interesting theory as to how and when those star patterns originated, as detailed in Appendix B.
After people had come to realise that events in the sky, such as the appearance of particular constellations, were correlated with the changing of the seasons, and could be used to predict seasonal events on Earth, it was perhaps a natural progression, within the viewpoint of geocentric cosmology, to imagine that celestial events somehow influenced, or caused, earthly ones – especially in those cultures which associated celestial bodies with their gods.
There was one particular correlation of an astronomical event with an earthly one, which may have played a major part in establishing this belief. The Egyptians attached great importance to Sirius, the brightest star in the sky, and by pure coincidence, they were able to use it to predict the most important natural phenomenon in their calendar – the annual flooding of the Nile. It’s no exaggeration to say that the very existence of their civilisation depended on this flooding, as it was what created a belt of fertile land in the middle of an arid desert. Indeed, there was a time when, for reasons unknown, the flooding didn’t happen for several successive years; the resultant crop failures led to a devastating famine, which almost wiped out the entire civilisation.
By a remarkable coincidence, the heliacal rising of Sirius – its first appearance in the morning sky, shortly before sunrise – occurred shortly before the flooding of the Nile. So when they first saw Sirius in the morning sky, they knew that the flooding was imminent, and it was time to plant their crops.
So given that such a celestial event, involving the brightest star of all, was so closely associated with an earthly one which was so vitally important, it was perhaps inevitable that the Egyptians came to believe that heavenly bodies influenced events on Earth! I speculate that this one apparent correlation may have been responsible, more than any other, for the origin of astrology as a belief system.
Given the belief that the heavens influenced the weather and other natural phenomena on Earth, it was probably not too great a step to assume that they also influenced or controlled every aspect of people’s lives. And so astrology, as we unfortunately know it, was born.
For many centuries, and in many cultures, belief in astrology was “mainstream”, and it was genuinely considered to be a “science”. Kings and politicians employed astrologers to advise them on affairs of state, when to conduct military campaigns, and so on. The science of positional astronomy – learning to predict the motions of celestial objects with ever-increasing accuracy – was first established in order to track those movements for astrological purposes, and great observatories were built for the purpose. “Scientific astrology”, and its close association with astronomy, persisted until the time of the Renaissance.

3.4. When it should have ended

For the sake of completeness, I’ll conclude this section with a very brief description of how the geocentric world view came to be proved wrong.
In mediaeval Europe, astronomers continued to study the motions of the planets, and compiled ever more accurate tables with which to predict them – still for the purpose of making astrological predictions. By the time of the Renaissance, people had found problems with Ptolemy’s cosmology; there were anomalies in the planetary motions, which it couldn’t quite explain.
During the Sixteenth Century, Nicolaus Copernicus ( 1473-1543 ) realised that the planetary motions could be better explained by assuming that the Sun was the centre of the Universe, and that the Earth was one of the planets which revolved around it. While he began writing about his ideas as early as 1507, his book was not published until shortly before his death. It’s commonly believed that he had not dared to publish it earlier, for fear of reprisals by the Church – but this is a myth. The book was published while he was on his deathbed, but only because he suffered a stroke while it was at the printers; he had sent it off before he became ill, and had in fact been circulating copies of the manuscript among his acquaintances for several years.
The most accurate planetary tables of all were compiled by Tycho Brahe ( 1546-1601 ). Tycho was one of the most meticulous observers ever to have lived – it’s something of a tragedy that he died just seven years before the invention of the telescope! – but he wasn’t much of a theorist; he stubbornly held onto the geocentric view, even after he himself found anomalies which it couldn’t explain.
After Tycho’s death, his assistant, Johannes Kepler ( 1571-1630 ), used his observations, together with rigorous mathematical analysis, to prove that the planets do indeed orbit the Sun, rather than the Earth. He also realised that their orbits are ellipses, rather than circles, and formulated what we now call the Three Laws of Planetary Motion – an important precursor of Newton’s Law of Gravity.
I’ll say a little more about Kepler. He lived at such a time as to be caught between the old world and the new; he was still influenced by ancient superstitions such as astrology, but at the same time, together with his contemporary Galileo, he was one of the founders of the modern scientific method. In the words of the late Carl Sagan, “the last scientific astrologer was the first astrophysicist”.1
In his youth, Kepler had invented his own model to try to explain the motions of the planets, which had more to do with mysticism and Greek philosophy than with modern science. He found that it didn’t work – so he abandoned it and started over again. Later, with the aid of Tycho’s observations, he hit upon the theory which we now know to be correct. This is exactly how real science works; if your theory or model doesn’t work, and can’t explain the observations, then you have to modify it - or even abandon it altogether and start again, as Kepler did - until you come up with one which does fit the observations!
During the same period, two astronomical events dealt a further blow to the established world view. In 1572 a very bright “new” star appeared in the sky, then gradually faded away over a period of several months. Another appeared in 1604. We now know that they were supernovae – the explosive deaths of massive stars - occurring within our own Galaxy. These events, which came to be named in honour of Tycho and Kepler respectively, proved that the heavens were not “perfect and unchanging”, as per the religious dogma of the time.
In 1608, astronomy was of course revolutionised, by the invention of the telescope. When Galileo Galilei ( 1564-1642 ) first turned a telescope to the sky the following year, what he found brought about the end of geocentric cosmology, once and for all. One of his first discoveries was that the Moon was not a perfect sphere of some unknown substance, as per religious dogma, but a world, with plains and highlands, mountains and craters. The discovery that Jupiter had four satellites orbiting it proved that it couldn’t possibly be “attached to a crystal sphere”, as per Ptolemy’s model. Within the next couple of decades, the observations of Galileo and others proved beyond doubt that the planets orbit the Sun, rather than the Earth.
Then in 1687, Sir Isaac Newton ( 1642-1727 ) published his Principia – probably the greatest mental effort ever undertaken by a single person – in which he formulated many of the laws of mechanics – including, of course, the inverse square law of gravitational attraction. The motions of heavenly bodies could be explained, not by invoking gods and magic, but by physics and mathematics.
Astronomers soon realised that even the Sun is not the centre of the Universe, but that it’s just one star among many, with no special place. By the early Twentieth Century, it was established that the Sun is a decidedly ordinary star, one of a hundred billion in our Galaxy alone, which in turn is just one of a hundred billion or more galaxies. And we now know that many, probably most, other stars have their own systems of planets. Far from the ancient idea of the Universe having been created for Man’s benefit, we now know that our place in it is nothing special whatsoever.
The concept of astrology as a “science” effectively died at the time of Galileo and Kepler, and the final nails were driven into its coffin by the time of Newton. There has been absolutely no place for it, in the mind of any rational thinker, for more than three centuries.


1. Carl Sagan, Cosmos, Macdonald, 1980.

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