Ptolemiac Astrology

Note: I published this on my website back in 2021, removed it, and then lost the original publication date.

At some point in time, everyone seems to experience confusion around tropical astrology. What the heck is it? Why aren’t the actual zodiac constellations important? Why does the March equinox always mean that it’s spring, even in the Southern Hemisphere? Why is it okay to use the bodies in the solar system that are only visible by a telescope, but the precession of the equinoxes doesn’t count? Why do we worry about the planets and the moon being in their correct position on the ecliptic, but the constellations don’t matter? Why does the astronomy apply in some cases but isn’t applicable in others?

And on a regular basis, I read or witness the usual discussion of tropical astrology versus sidereal astrology. But as I was explaining Ptolemy’s concept of the universe to another astrologer, I had a sudden realization. Astrologers were dealing with a nomenclature issue rather than an astrology issue. Perhaps it would be easier if astrologers stopped using the term ‘tropical’.

It occurred to me that two key issues have been a source of confusion since the revival of astrology in the Western world during the 19th century.

The first problem is the term ‘tropical’ astrology. It’s supposed to convey that astrology is concerned with the passing of the seasons in the Northern Hemisphere. Each thirty-degree slice of sky represents the sun’s progression through the seasons. However, we use a tropical (solar) year on Earth (365 days a year). Typically a person wonders why tropical astrology is different from what can be seen in the sky when we use a tropical year. Additionally, the word ‘tropical’ typically makes the uninitiated think of countries close to the equator.

Merriam Webster defines ‘topical’ as:

1a: of, relating to, occurring in, or suitable for use in the tropics // tropical forests // a tropical disease

b: of, being, or characteristic of a region or climate that is frost free with temperatures high enough to support year-round plant growth given sufficient moisture // tropical Florida

The second problem is that Western astrology has one foot in Ptolemaic astrology and one foot in modern astronomy. Western astrologers use Ptolemy’s astrology work, the Tetrabiblos, but do not utilize his astronomical model and calculations from the Almagest. This is something of a problem because Ptolemy intends for these two works to be used together for the purposes of astrology.

I’ve written about this in another article, but in summary, the Ptolemaic astronomical model consists of the following basic principles. (These principles were not new when he documented them and were widely accepted across the ancient world. Ptolemy, however, was able to use his model to better explain the rate of planetary motion.)

1. The model is geocentric. Earth is the center of the model.

2. The five visible planets, along with the sun and moon are moving in their own spheres. The spheres are circles.

3. The constellations are in the furthest sphere and remain fixed.

4. The movement of the planets, sun, and moon is explained with deferent and epicycle equations.

5. The order of the solar system and universe (where earth is the center) is Earth, Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, and the fixed stars.

Interestingly, despite Ptolemy’s model being geocentric (and Ptolemy in all likelihood appropriating other ancient astronomer’s data), the epicycle calculations produced fairly accurate results most of the time. In Ptolemy’s model, the bodies in the sky that appear to move the fastest are (logically) closer to earth, and the slower bodies are further away. This produces the order of the moon, then Mercury, Venus, etc.

https://en.wikipedia.org/wiki/Deferent_and_epicycle

Ptolemy developed his astrological treatise, the Tetrabiblos based on his astronomical theories (and his order of the solar system) and Aristotle’s descriptions of the elements.

Which explains why Ptolemy wrote, “Mercury sometimes produces dryness, and at other times moisture, and each with equal vigor. His faculty of absorbing moisture and creating dryness proceeds from his situation with regards to the Sun, from which is at no time far distant in longitude; and on the other hand, he produces moisture because he borders upon the Moon’s sphere which is nearest to earth.” (J. M Ashmand translation.)

The use of both the Tetrabiblos (astrology) and the Almagest (astronomy) presented a major challenge for the revival of Western astrology. Ptolemy’s astronomical theories were invalid (even though his calculations still produced reasonable results).

It’s therefore understandable that tropical astrology settled into a strange dichotomy of using Ptolemy’s astrology coupled with modern astronomy. On the whole, astrologers tend to be rational people. They may have a love of astrology, but the vast majority of them are also keen science nerds. They know the earth is a globe, that the sun is at the center of the solar system, science is awesome, and history has a lot to teach us. In the revival of astrology, no rational astrologer would want to admit that they practiced Ptolemaic astrology and Ptolemaic astronomy.

However, when only one part of Ptolemy’s model is used, the results are a weird mashup. Spring is always signified by Aries, the planet’s qualities don’t quite align with their modern astronomical properties, and the precession of the equinoxes doesn’t matter. But at the same time, everyone tries to take a great deal of care (including using the Swiss ephemeris to calculate planetary motion) to ensure the planets are in their correct position on the ecliptic. Even though, due to the complications of using ephemerides, Delta T predictions, and epochs, they're not. They're close. But not consistently.

In that light, perhaps it’s time that astrologers acknowledged that the Tetrabiblos and modern astronomy don’t work with each other. Additionally, astrologers should acknowledge that the full Ptolemaic model of astrology isn’t utilized despite what tropical astrologers say. Ptolemy intended for the Tetrabiblos and the Almagest to work together. In Ptolemy’s version of astrology, the model is geocentric, the order of the planets is as Ptolemy stated, and orbits are calculated using deferents and epicycles. Astrology software could ditch their statements about using the Swiss ephemeris and use the Ptolemy’s equations and models instead. In this day and age, computers would be sophisticated enough to incorporate even the (presumably) complicated epicycle equations required for Uranus, Neptune, and Pluto.

If this approach was taken, Ptolemy’s model would be whole again. The significations and delineations in the Tetrabiblos would be aligned with the Almagest, resulting in a complete system of astrology.

More importantly, complete adoption of the Ptolemaic astrological and astronomical model shuts down the confusion. Because in terms of the ‘schools’ of astrology, all an astrologer has to say is, “I’m a Ptolemaic astrologer.” Those four words express the entire system the astrologer practices in a more clear and concise way than saying, “I’m a tropical astrologer.”

Anyone can search for what the Ptolemaic model and they will find most of their information on various Physics department sites. They can read the Tetrabiblos and Almagest online. Even astronomers would respect this stance. Astrologers would have selected a clear and complete model and that model could be used to its fullest. More importantly, no one would be twisting themselves into knots trying to explain a school of astrology that insists of using some aspects of modern astronomy while ignoring others.

The confusion that accompanies someone saying they’re a tropical astrologer would evaporate. Long involved discussions of why some things apply (the elliptical orbit of the planets) but other things do not (the precession of the equinoxes) disappear along with the confusion.

“I’m a Ptolemaic astrologer” may just be the one thing that makes the Western form of astrology completely understandable to everyone.