Welcome back to Birth Charts 101, a semi-regular series on the basics of interpreting your natal chart! Last time, we learned how to draw a simple natal chart by hand.
This time, we’re going to take a step back to understand one of the foundations of what we’re actually talking about when we discuss astrology: the zodiac.
Why, exactly, do we use this particular collection of twelve signs in astrology, derived from certain constellations but not others? (Which is another way of asking, why can’t I have the Big Dipper as my sun sign??) Where do the signs get their meanings from? What about the different types of zodiacs used in astrology (tropical vs. sidereal)? How is the zodiac represented in the natal chart?
These are some of the questions I often hear from people seeking to gain a deeper understanding of their natal chart. We’ll be exploring some of them here (hopefully lightly and painlessly).
“As above, so below.”
This quotation is likely familiar to astrology enthusiasts. It’s accepted as a philosophical statement encapsulating the dynamic believed to be at work in astrology: that events shown by the movements of the planets play out on earth, in our lives.
The quote is actually an English paraphrase of a Latin translation of a line from the Emerald Tablet, an late 8th-or early 9th-century Arabic work. This work was itself a translation of a cryptic Hermetic text attributed to the legendary Hellenistic figure Hermes Trismegistus, who was often cited as a source of wisdom by ancient astrologers. (This is a similar pedigree for most ancient astrological texts — a translation of a translation of a fragment of a translation.)
A more literal translation of the Arabic is:
“That which is above is from that which is below, and that which is below is from that which is above.”
Leaving aside for the moment the philosophical implications of the more literal translation, that the two spheres — earthly and celestial — influence each other, this idea gets to the heart of what we’re talking about when we discuss astrology, that people observing the heavens over the course of human history have found patterns that relate to human activity.
But, what were (and are) people actually looking at?
The Path of the Sun
Early stargazers noted that there were different types of celestial bodies, the so-called “wandering stars,” the five visible planets plus the luminaries (sun and moon), which moved in the sky, and the “fixed stars,” which remained static.
Groupings of fixed stars suggested shapes or designs in the night sky to creative observers, who often imbued them with mythological or religious meaning. It was against these constellations of fixed stars that the “wandering stars” moved.
The zodiac, the collection of twelve signs used in astrology, derives from the constellations that the luminaries and visible planets pass through on the ecliptic, the apparent path of the sun, as observed from Earth.
The planets and luminaries pass through the same constellations in the same order, though at varying rates, which are reflected in the signs of the constellational zodiac — first Aires the ram, then Taurus the bull, Gemini the twins, and so on, finally returning to Aires. (Sorry, no Orion planetary placements for you! The planets simply don’t go there.)
However, the constellations are of unequal sizes in the sky. Early astronomers (who were also astrologers, as these approaches were fused then) divided the constellational zodiac into twelve equal divisions of 30 degrees each, totaling 360 degrees for a full revolution of the sun.
This video does a nice job of showing the sun’s path through the ecliptic, as well as explaining the phenomenon known as “precession,” the gradual shift in the orientation of Earth’s axis of rotation, and how this has slowly changed when the sun passes through different parts of the constellational zodiac. (And props to this planetarium guy for not automatically trashing astrology :)
Tropical Vs. Sidereal
As Chris Brennen notes in Hellenistic Astrology: The Study of Fate and Fortune, the original astrological zodiac, known as the sidereal zodiac (from Latin sidereus, “of the stars”), which divided the ecliptic into twelve equal 30 degree signs, represents an idealized or symbolic division of the constellations1.
At the time that Hellenistic astrology developed, around the late second or early first century BCE, the sidereal division of the zodiac aligned with the seasons, with the cardinal signs of Aires, Cancer, Libra, and Capricorn each beginning a season.
The seasonal distinctions became incorporated into many of the significations of the signs, for example, the association of Aires with the energy of budding spring blooms. This interpretive knowledge became codified through the “tropical” zodiac, which aligns the spring equinox in the northern hemisphere with zero degrees of Aires.
However, over time, the precession of the equinoxes slowly caused the sidereal zodiac to deviate from the tropical zodiac.
At first it was a matter of a few degrees; now, in the 21st-century, the difference is about 24 degrees.
Which is why, if you visit a practitioner of Indian astrology, which uses the sidereal zodiac and Hellenistic techniques combined with indigenous lunar techniques, there’s a good chance that most or all of your planetary placements will be one sign earlier. For example, I’m a tropical Pisces sun but an Aquarius sun using the sidereal zodiac.
The issue of which zodiac to use is a bit of a divisive issue among contemporary astrologers, with passionate denunciations of one by supporters of the other. Most modern astrologers not following the Indian tradition use the tropical zodiac, and this is the default setting on most astrology apps and online calculators. However, there is a growing practice of “Western” sidereal astrology, which uses the sidereal zodiac with prevailing non-Indian astrological techniques.
Daily Rotation Plus Movement Through the Ecliptic
The natal chart represents the ecliptic — the path the planets follow through the constellations as seen from Earth — as a two dimensional circle.
But the circle isn’t static.
One of the main innovations of Hellenistic astrology, which is the basis for modern astrology, was that it overlaid a diurnal, or daily, motion over the movement of the planets and luminaries through the zodiac.
This synthesis, of two ancient practices of astrology from Egypt and Mesopotamia, respectively, allowed for the invention of “horoscopic” astrology, in which a chart is created for an event, such a person’s birth, based on the time it happened (or will happen), in order to derive meaning about that event.
Every day, the sun passes through all twelve signs of the zodiac, spending about two hours in each. The sign on the horizon at any given time is the “rising” sign, or Ascendant, if a chart were to be cast for that moment.
Fun fact: at sunrise the rising sign is always the same as the sign the sun is currently passing through; at sunset, the rising sign is the opposite sign to the sun. Today, with the sun in Aires, at sunrise the sign rising was also Aires; at sunset, the sign rising will be Libra, the sign opposite Aires.
In a natal chart, the rising sign is the sign on the eastern horizon at the time of birth, represented as a point on the left-hand side of the chart. Sometime later, anywhere to a few minutes to a couple of hours later, the rising sign shifts to the next sign in zodiacal order. It’s a bit like a combination lock, which turns clockwise.
For example, here’s the chart of the moment I’m writing this, with Virgo rising (shown by “As”) at 28 degrees, towards the end of Virgo.
A few moments later the rising sign shifted into Libra, where it will stay for a couple of hours, heading into sunset. The planets are all in the same signs, but have all shifted by one house position.
Okay, that was fun, but not as fun as imagining we’re traveling through the zodiac itself, interacting with the planets, accompanied by some nice music. Here’s Coldplay, with an intro to their Music of the Spheres:
Chris Brennen, Hellenistic Astrology: The Study of Fate and Fortune, 2017, page 216.