Introduction to Zodiac Signs – 1:
Basis of the Zodiac; Sign Groupings; Great Ages

– written by Philip Graves, Summer 2002
– expanded to four parts, 3rd January, 2004
– reformatted for WordPress, June 10th, 2016


What are zodiac sign placements?

The zodiac is a division of the space around the earth into segments called ‘signs’. It is centred in a band of space called the ‘ecliptic‘, which is the projected 360º circle around the earth in which the sun, moon and planets appear to circuit relative to the earth. In reality, of course, the earth and the planets are all orbiting around the Sun on this plane, but in astrology we are interested in what affects us here on earth, so what matters is the positions of the Sun, Moon and planets relative to the Earth!

The ecliptic is demarcated in degrees longitude; and whatever method may be used to divide it up into signs, fit is worth bearing in mind that it is equally a continuum, and that when astrological influences are being assessed much more precise degree-specific calculations frequently have to be made. For any given person, at the moment of birth, the Sun, Moon, planets and various other factors will each be located in one of the signs of the zodiac.

There are two completely different methods for dividing up the ecliptic into zodiac signs: the sidereal method and the tropical method. Both sidereal and tropical astrology have been practised for thousands of years, and each has its own observable validity. The signs of the sidereal zodiac, also called the fixed zodiac, are located in different places from those of the tropical zodiac (or ‘moveable zodiac’), though at certain points in history, most notably around 221 A.D., they have happened to coincide with them temporarily.

The astronomical bases and astrological effects of the sidereal signs are entirely separate from those of the tropical signs, although confusingly they have inherited a matching set of names. These names are those of the most obvious constellations of stars that lie behind the ecliptic as viewed from earth.

The sidereal zodiac is carved out in accordance with the positions of those constellations; and its supposed effects are based on their positions. In some sidereal traditions, upwards of 12 sidereal zodiac signs have been in use, including additional constellations; but 12 equal signs is the most usual.

The tropical zodiac is based instead on the interface between the ecliptic and the earth’s equator, a principle bearing no relation to the positions of the constellations; but its 12 signs were named after 12 of the constellations to reflect the fact that, when these signs were named about 2,000 years ago, their locations approximated to those of the constellations in question, although the two zodiacs have since mutually drifted apart by 24º. The cyclical revolution of the tropical zodiac about the fixed zodiac does not compromise or weaken the astrological influence of the tropical signs, which at any point in history operates independently of the positions of the constellations sharing their names.

It is important not to attempt to interpret placements of the planets etc. in the signs of the tropical zodiac using sources on their placement in the signs of the sidereal zodiac that bear the same names, or vice versa. They are fundamentally totally different and cannot be mutually substituted. The vast mass of western literature on astrology refers to and interprets placements in the tropical zodiac.


The basis of the tropical zodiac

The earth revolves once a day around its lateral axis, known as the equator. The ecliptic is angled at a considerable slant relative to the equator, and intersects it twice, one point of intersection being exactly opposite the other, and these points being called the ‘equinoxes‘ while for the rest of its path it is inclined to the north or south, in equal measure; and its most extreme northern and southern points are known as the tropic of Cancer and the tropic of Capricorn respectively. The equinox where the Sun, Moon and planets are heading generally northwards is known as the vernal or Spring equinox, while the one where they are heading southwards is known as the Autumn equinox.

At certain times, all planets from Mercury to Pluto move temporarily in the opposite direction from normal within the ecliptic as viewed from Earth; this apparent retrograde motion results from the fact that the Earth itself is really moving too, but they make up for it by moving in direct motion at 2-3 times their average speeds at certain other times, and always complete their circuits of the ecliptic in a fairly uniform length of time or period ultimately.

The incline of ecliptic relative to the equator is most obvious to us in the seasons caused by the movement of the Sun through the ecliptic. The unit of time we all know as a year is simply the amount of time the Sun takes to complete one circuit of the ecliptic. In the northern hemisphere, when the Sun reaches the tropic of Cancer, around June 21st, we naturally experience the longest and strongest hours of sunlight, because it is at its furthest northward inclination in the ecliptic; this time is known to us as the summer solstice; while when it reaches the tropic of Capricorn we experience the shortest and weakest sunlight because it is at its furthest southward point; this time is known to us as the winter solstice. When it reaches the Autumn and Spring equinoxes, since it is directly over the equator, we get average sunlight and day length for the year.

The two equinoxes and two tropics are the most basic four points on the tropical zodiac. These four points naturally divide the full 360º ecliptic into four quadrants of 90º each. Each quadrant of the ecliptic is further subdivided by astrologers into three equal zodiac ‘signs’ of 30º each, numbered from 0º to 29º.


Signs of the tropical zodiac

The Spring equinox is taken as being the beginning of the tropical zodiac, and the first quadrant embraces the path through the ecliptic from the Spring equinox to the northernmost point, the Tropic of Cancer, and corresponds exactly to the season we call ‘Spring’, as far as the path of the Sun is concerned. This quadrant is divided into the signs known as Aries, Taurus and Gemini.

The second quadrant, from the Tropic of Cancer through to the Autumn equinox, is divided into the signs Cancer, Leo and Virgo, and corresponds to the season we call ‘Summer’ when the Sun passes through it.

The third quadrant, from the Autumn equinox to the southernmost point, the Tropic of Capricorn, corresponds in Sun terms to the season we call ‘Autumn’, and is divided into the signs Libra, Scorpio and Sagittarius.

The fourth quadrant, from the Tropic of Capricorn back to the Spring equinox, is divided into the signs Capricorn, Aquarius and Pisces, and corresponds to the solar season we call ‘Winter’.

The table below shows the four sign quadrants of the tropical zodiac and their division each into three signs. Also shown are the defining entry point along the path of the geocentric ecliptic at which the quadrant begins, the declination of each quadrant north or south of the equator, and the direction in which this declination is moving (northward or southward) as the journey through the quadrant concerned progresses.

Point of entry Declin. Direction Signs Cardinal Fixed Mutable
Vernal Equinox North Northward 1-3 Aries Taurus Gemini
Tropic of Can. North Southward 4-6 Cancer Leo Virgo
Autumn Equinox South Southward 7-9 Libra Scorpio Sagitt.
Tropic of Cap. South Northward 10-12 Capricorn Aquarius Pisces

NB: In the above table, ‘Declin.’ denotes ‘Declination’


Sign groupings

Each of the three signs in each quadrant of the zodiac is known as being of a different ‘mode‘, quality or constitution from the other two. The first of the three signs in each quadrant is known as being ‘cardinal‘; the second in each is known as being ‘fixed‘; and the third as being ‘mutable‘ – as shown in the table above also. These three groupings each of four signs of a particular mode are sometimes known as the ‘quadruplicities‘. Thus, the cardinal signs are Aries, Cancer, Libra and Capricorn, the fixed ones are Taurus, Leo, Scorpio and Aquarius, and the mutable ones are Gemini, Virgo, Sagittarius and Pisces. Signs of the same mode are always located three signs apart from each other.

Signs Cardinal Fixed Mutable
1-3 Aries Taurus Gemini
4-6 Cancer Leo Virgo
7-9 Libra Scorpio Sagittarius
10-12 Capricorn Aquarius Pisces


The zodiac is also divided for sign classification purposes into three sections of 120º, as shown in the table below, again starting from the Spring equinox, otherwise known as Aries 0º. The first section therefore encompasses the signs Aries, Taurus, Gemini and Cancer; the second encompasses Leo, Virgo, Libra and Scorpio; and the third encompasses Sagittarius, Capricorn, Aquarius and Pisces. Each of the four signs in each of these sections is known as being of a different ‘element‘ from the other three in its section. The first of the four signs in each section is known as being of the element ‘Fire‘; the second in each is known as being of the element ‘Earth‘; the third in each is known as being of the element ‘Air‘; and the fourth in each is known as being of the element ‘Water‘. These four groupings each of three signs of a particular element are sometimes termed the ‘triplicities‘. Thus, the Fire signs are Aries, Leo and Sagittarius; the Earth signs are Taurus, Virgo and Capricorn; the Air signs are Gemini, Libra and Aquarius; and the Water signs are Cancer, Scorpio and Pisces. Signs of the same element are always located four signs apart from each other.

Signs Fire Earth Air Water
1-4 Aries Taurus Gemini Cancer
5-8 Leo Virgo Libra Scorpio
9-12 Sagittarius Capricorn Aquarius Pisces


Precession of the equinoxes

Having expounded the astronomical derivation of the tropical zodiac, we now can revisit the question of how and why it moves in relation to the sidereal one (fixed by the backdrop of the stars). This is caused (in simple terms – to avoid delving into advanced physics) by a slow oscillating movement of the Earth called nutation that results from the gravitational pull exerted by the Sun and Moon on its equator.

A given point in the tropical zodiac will move in retrograde direction through a complete circuit of the fixed (sidereal) zodiac in a period of time that itself varies in length significantly over the course of history as our Solar System moves relative to other stars in the Milky Way, but is currently scientifically estimated to be about 25,770 years. This unit of time has been named the Great Year.


The Great Ages

The fixed (sidereal) zodiac, like the tropical zodiac, has been carved into twelve signs each of equal 30º arc. By taking the vernal point (i.e. 0º Aries in the tropical zodiac) as our primary reference point and observing how it coincides with the backdrop of the fixed zodiac at any point in time, we can declare that we are in a Great Age corresponding to the name of the sidereal sign in which the vernal point is currently found. According to the model of the sidereal zodiac popularised by Fagin and Bradley, the vernal point last crossed 0º Aries in the fixed zodiac around 221 A.D.. The Great Year, divided into the twelve sidereal signs, works out to about 2147.5 years per sign. This means that by Fagin and Bradley’s measure the Earth has have been experiencing the Great Age of Pisces since 221 A.D. and will continue to do so until about 2368 A.D., when the Great Age of Aquarius will commence.

However, it is worth remembering that the sidereal zodiac, while supposedly fixed against the constellations, is an arbitrary device, rounded up into thirty-degree signs, when the constellations themselves are not. Therefore, depending on where they choose to draw the boundaries between the constellations, astrologers frequently depart from Fagin and Bradley’s model and arrive at variant views of the time at which the vernal point should be held to pass from one sidereal sign to the next. A fine example of this is found in the practice of stellar astrology, a model of sidereal astrology which instead of rounding up the constellations into equal signs delimits their starts and ends individually, in accordance with their exact boundaries, allowing thus for their differing natural arc coverages.

Robert Hand noted that if the dawning of the Age of Pisces was referenced from the time when the first star in the constellation Pisces was passed through by the vernal point, the Age of Pisces could be said to have begun around 111 B.C.. If 2147.5 years were added to this year to represent the standardised duration of a Great Age, we would have a projected date of around 2036 A.D. for entry into the Age of Aquarius. Yet, Hand also noted that the vernal point would pass through the last star in the constellation Pisces in 2813 A.D.. On that measure, the inhabitants of the Earth will not experience the Age of Aquarius for the next eight centuries.

It should be borne in mind that there has been much hype and speculation with regard to the influence of the Great Ages on cycles of human history and mass consciousness in the last fifty years, but that prior to the 19th century the precession of the equinoxes was not regarded as a phenomenon of any noteworthy astrological impact at all. From the point of view of tropical astrology, the only significant factor to take into consideration with precession is the gradual displacement within the tropical zodiac of the individual major fixed stars which, when closely conjunct a point in the birth chart, are believed to have a bearing on the life of the individual.

If there is any generalised influence exacted by the passing of the vernal point through the sidereal signs, or more accurately the constellations, then it is likely to relate in character to the qualities ascribed to the constellations being transited by it, but certainly not to the tropical signs of the same name. Thus the Age of Pisces would be influential in accordance with the meaning of Pisces as a sidereal sign, which is altogether distinct from Pisces as a tropical sign; and the same principle applies to the Age of Aquarius, many popular speculative attributions of characteristics to which betray their derivation in preconceived notions of the nature of the tropical sign Aquarius, which in the context of the Age of Aquarius is both astronomically and astrologically immaterial. A thorough grounding in sidereal astrology, and, more specifically, the influences ascribed by it to each sidereal sign, as distinct from the like-named tropical sign, is surely needed for the Great Ages to be astrologically interpreted with any authority or accuracy.


Continue to Part Two of Four…

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