What Are Decans? The 36 Faces of the Zodiac Signs

Introduction

A sign is a thirty degree arc in the sky. But classical astrology has never treated that arc as an indivisible whole. Inside every sign there are finer distinctions, smaller chambers, and one of the most elegant of these chambers is the decan. Each sign is divided into three equal parts, ten degree segments. Across the whole zodiac this produces 12 x 3 = 36 decans. These thirty six gates are rooted both in the night sky of Ancient Egypt and in the table of dignities used by Hellenistic astrologers.

In English, the decan is often translated as the "face," and in traditional texts it appears under the Latin facies and the Arabic wajh. The two concepts are intertwined but not identical: the decan is the segment itself, while the face is the system of planetary rulers assigned to that segment. In this article we will look, with classical accuracy, at the Egyptian origin of decans, how they were carried into Hellenistic astrology, the two separate ruler systems, their place in the table of dignities, and the talismanic images of the Picatrix.

The Egyptian Origin of Decans

The decan system was born not in the zodiac but in the night sky of Ancient Egypt. Egyptian sky observers identified thirty six stars, or groups of stars, that rose at regular intervals along the horizon. These stars are called decans (from the Greek dekanos, meaning "of ten"). Each decan marked a particular hour of the night for roughly a ten day span of the year: when a decan appeared on the horizon, a new hour of the night was considered to have begun.

Ten days for each of these thirty six decans adds up to 360 days; adding the 5 epagomenal, or intercalary, days completes the 365 day Egyptian civil year. The anchor of the whole sequence is the star Sothis (Sirius), the herald of the new year. The heliacal rising of Sirius, its reappearance just before dawn after a period of invisibility, marked the new year and the flooding of the Nile in Egypt. The decan system thus functioned as a star clock: the sky itself worked like a vast dial for reading the hours of the night.

Two separate charting traditions of this star clock are known. The diagonal star clock is found on coffin lids from the Middle Kingdom period (around 2100 BCE) and is based on the decan's rising on the eastern horizon. The transit star clock, known from the New Kingdom period, most notably from the tomb ceiling of Senenmut (TT 353, around 1463 BCE), is based on the decan's transit across the meridian, its upper culmination. Both systems share the same thirty six fold structure; only the celestial event that marks the hour differs.

Decans in Hellenistic Astrology

Egypt's star decans merged with the Babylonian derived zodiac during the Hellenistic period (from roughly the 2nd century BCE onward). Astrologers rearranged the thirty six decans so that each of the twelve signs was divided into three, with each decan exactly ten degrees. In this way the star groups that had once marked the sky became bound to degrees of the zodiac.

This mapping turned decans from mere calendar markers into units carrying astrological meaning. Late Egyptian and Hellenistic sources attribute rising stars, or paranatellonta, to each decan: the constellations and stars that appeared on the horizon together with a rising decan. Teukros (1st century BCE, Teukros of Babylon) and later Hephaistio (5th century CE, of Thebes) are the principal sources that transmit these lists of paranatellonta and decan images. This tradition endowed the decans with a rich symbolism, giving each ten degree segment its own character and its own figure.

Decans are part of the broader classical technical repertoire. Knowing not only which sign a planet occupies but also which decan of that sign refines interpretation. This is considered together with other layers that divide a sign, such as elements and modalities; just as aspects describe the relationship between planets, decans refine a planet's position within its sign.

Two Systems of Decan Rulership

Here is a point of classical astrology that is often confused: there are two separate systems that assign planetary rulers to decans. Both are legitimate, but they serve different purposes and produce different results.

1. The Chaldean Order (the "Face" System)

This is the system used for dignity in the Western tradition. The Chaldean order is a classical sequence that arranges the planets by their apparent speed, or their distance from Earth, from slowest to fastest: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. In the face system this order is distributed starting from the first decan of Aries, beginning with the fastest planet.

The first decan of Aries (0 to 10 degrees) falls to Mars, the second decan (10 to 20 degrees) to the Sun, and the third decan (20 to 30 degrees) to Venus. Taurus's first decan continues with Mercury, then the Moon, then Saturn, then Jupiter, and the cycle turns without interruption through all thirty six decans. This order is the Chaldean planetary order read in reverse, and it shares the same logic as the system of planetary hours. For this reason, the "face" is also a close relative of the idea of the planetary hour.

2. The Triplicity System

The second system ties decans to the element, that is, the triplicity, of each sign. In this system, the three decans of a sign are assigned in turn to the rulers of the signs sharing that element (fire, earth, air, water). For example, in the fire triplicity (Aries, Leo, Sagittarius), the first decan falls to that sign's own ruler, and the following decans fall to the rulers of the other two signs of the same element. This approach corresponds to the drekkana division of Hindu astrology and reads decans through the logic of the elements.

It is important not to confuse these two systems. When an astrologer says a planet is "in its own decan," it matters which system is meant. In the Western classical tradition, when dignity is being discussed, it is almost always the Chaldean face system that is used; the triplicity based decan appears more often in the Hindu tradition and in comparative studies.

Sign	1st Decan (0-10°)	2nd Decan (10-20°)	3rd Decan (20-30°)
Aries	Mars	Sun	Venus
Taurus	Mercury	Moon	Saturn
Gemini	Jupiter	Mars	Sun
Cancer	Venus	Mercury	Moon
Leo	Saturn	Jupiter	Mars
Virgo	Sun	Venus	Mercury

The table above shows the distribution of the Chaldean face system across the first six signs. Notice that the rulers flow endlessly in the same order (Mars, Sun, Venus, Mercury, Moon, Saturn, Jupiter); sign boundaries never interrupt this flow. The same cycle continues without a break through the remaining six signs, and the last decan of Pisces closes with Mars, completing the ring.

The Place of Decans (Faces) in the Table of Dignities

In classical astrology, a planet's strength is assessed according to the position it occupies. There are five fundamental grades of dignity, from strongest to weakest:

1. Domicile (rulership): The planet is in its own home; the strongest position. It is as if the person is in their own house.
2. Exaltation: The planet is in the sign where it is honored; like an esteemed guest.
3. Triplicity: The planet is a ruler of its own element; it is in a supportive environment.
4. Term (bound): The planet is within its own bound; like holding a small property.
5. Face (decan): The planet is in its own face; the weakest dignity. Just a foothold.

As you can see, the face is the lowest rung on the ladder of dignity. Classical texts describe it with a striking image: a planet in its own face resembles a person who has "barely turned back from the brink of a fall," managing to hold themselves upright with difficulty. It is not comfortable, it is not strong, but neither is it entirely without recourse. It carries a small measure of wellbeing, a trace of dignity, however modest.

The real practical value of the face is this: if a planet has no strong dignity at all, at least being in its own face saves it from being a stranger, or peregrine. In traditional astrology, a "peregrine" planet is one with no dignity whatsoever, a homeless wanderer, and it is considered a negative indicator, particularly in horary astrology. Being in one's own face gives a planet some belonging, however weak, and the saying goes that it is "better than nothing." For this reason, the face is a small, but not negligible, grade of dignity.

A planet in its own face is like a man sitting at his own door but unable to enter his house: neither fully inside nor fully outside, a small shelter, but a shelter nonetheless.

Picatrix and the Images of the Decans

One of the most fascinating aspects of the decans is the symbolic image attributed to each one. This tradition reaches back to Teukros and was gathered in detail in the famous medieval magical astrological handbook Picatrix (its Arabic original, the Ghāyat al-Ḥakīm, "The Aim of the Sage," dating to roughly the 10th to 11th century CE).

The Picatrix describes each of the thirty six decans with a vivid image: figures wearing particular garments, people holding tools or weapons in their hands, animals, kingly or ascetic appearances. For the first decan of Aries, for example, a standing figure holding a specific object and dressed in specific colors is described. These images served both to fix the character of a decan in memory and to be used in the making of talismans, which was the Picatrix's central concern.

The logic of traditional talismanic practice ran as follows: while the relevant decan was rising on the horizon and its associated planet was in a favorable position, engraving the decan's image on a suitable material (a stone, a metal) was thought to gather the celestial power of that decan into the object and direct it toward a particular purpose. This turned decans from mere units of interpretation into tools of operative astrology. The decan images of the Picatrix also drew considerable interest during the Renaissance, influencing the understanding of celestial talismans held by thinkers such as Marsilio Ficino.

Using Decans in Practice

How do you read decans in your own birth chart? Here is a simple road map:

1. Look at the planet's degree. By its degree within the sign: 0 to 10 degrees is the first decan, 10 to 20 degrees the second decan, 20 to 30 degrees the third decan. For example, a planet at 17.4 degrees Leo sits in Leo's second decan.
2. Identify the face ruler. Check the Chaldean face table to see which planet rules that decan. Is the planet in its own face? If so, it has a dignity, however weak.
3. Evaluate the whole picture of dignity. The face is not interpreted alone. Look at it together with the planet's condition in domicile, exaltation, triplicity, and term. The face is the lightest but complementary layer of that picture.
4. Add the symbolic layer. If you wish, you can also consider the decan's image and its paranatellonta; this brings a traditional depth to interpretation.
5. Explore the Egyptian star clock layer. If you want to see the Egyptian, star clock dimension of a decan, you can use a tool that calculates the decan of your birth moment together with its Hellenistic sign and degree equivalent.

The golden rule of classical interpretation is this: the primary weight always rests with the sign the decan belongs to, and with that sign's ruler. The decan is a fine embroidery added on top of that whole; on its own it does not determine a chart, but used correctly it lends a reading elegance and precision.