Cultural Epochs and Astronomy


One must distinguish between 4 things

a- sidereal constellations of the zodiac
b- sidereal signs of the zodiac
c- tropical signs of the zodiac
d- Steiner cultural epochs

They can be described as 4 different concentric zodiacs or circles, all of them seemingly rotating with respect to the other along the sun's path or ecliptic, and differing among themselves by:

a- the way it is divided (i.e. equal or unequal divisions)
b- the starting zero point
c- the speed of rotation

Steiner's cultural epochs ("d") is the least astronomical of the 4. It is based on a cycle of exactly 25920 years, traditionally (but wrongly) wrongly called "platonic year", divided in 12 equal 30 degree sections rotating at a speed of exactly 30 degrees per 2160 years. This is only roughly based on astronomy, and is grounded more on tradition and numerology. Steiner never had this clear, and --by giving exact dates-- made a great confusion out of it.. Its starting zero point is given by Steiner as 747 BC, the traditional year of the foundation of Rome, corresponding to the start of the 4th post-Atlantean epoch and the development of the rational soul, and identified more or less correctly --as we shall see-- with the constellation of Aries.

The zodiac of the constellations ("a") is rigorously astronomic and experiential, and is the only one that has a direct, unambiguous relationship to the stars. It is not made of 12 constellations but 13 (Ophiucus) and all are of unequal length. (Aries 24 degrees, Virgo 43, Scorpio 6, Ophiucus 22, Cancer 20, Pisces 36, Aquarius 24, etc.). These lengths are of course mere international conventions, but they were the product of a consensus among all classical and modern authorities on the subject. Since it is sidereal, it doesn't rotate and is fixed in quasi-inertial space. Its starting zero point is the line that divides Aries with Pisces, and was drawn more or less arbitrarily by the International Astronomical Union with great precision in 1928.

The sidereal signs of the zodiac ("b") is also fixed in space, but is divided in 12 equal signs that roughly correspond to the constellation asterisms behind them. How rough the correspondence is can be seen by comparing the sidereal sign of Virgo (30 degrees of the sun's path) with the corresponding constellation (43 degrees), or the sidereal sign of Cancer (30 degrees) with its corresponding constellation (20 degrees). Its starting zero point is an object of controversy and of historical research, and varies within a range of few degrees depending on the historical tradition followed, be it mainly Indian, Baylonian, Egyptian, etc. The most widely accepted zero point in the West --adopted for example by Robert Powell-- coincides very closely with a position of the star Spica in 29 Virgo, Aldebaran in 15 Taurus, and Antares in 15 Scorpio, and belongs to the Babylonian astronomical and astrological tradition.

The last one is the tropical zodiac ("c"), tied to the solstices and equinoxes and completely independent of the stars or constellations. Its starting point is the vernal equinox, which rotates backwards along the fixed sidereal reference frame at a speed equal to the general precession in longitude (50.28" per year at present). The complete cycle is constant and takes 25700 years. This cycle of the vernal equinox retrograding along the sidereal signs and constellations is the measuring stick or clock handle used to establish the so-called cosmical rhythm of cultural evolution. But we must differentiate between this cycle and the cycle of cultural epochs used by Steiner.

International Astronomical Union: Zodiacal Constellations 

constellation border in 1979
length Date of Sun's entry in 1979 Duration of Sun's stay in days Total area in square degrees
Capricornus 29,21:46 Capricorn 27,49'57" Jan 20 27.44 414
Aquarius 27,11:43 Aquarius 24,27'42" Feb 16 24.06 980
Pisces 21,39:25 Pisces 36,44'25" Mar 12 37.51 889
Aries 28,23:50 Aries 24,43'51" Apl 19 25.48 441
Taurus 23,07:41 Taurus 36,43'26" May 14 38.31 797
Gemini 29,51:07 Gemini 27,50'56" Jun 21 29.20 514
Cancer 27,42:03 Cancer 20,03'04" Jul 21 20.96 506
Leo 17,45:07 Leo 35,48'50" Aug 11 37.05 947
Virgo 23,33:57 Virgo 43,57'40" Sept 17 44.51 1294
Libra 07,31:37 Scorpio 22,54'24" Oct 31 23.10 538
Scorpius 00,26:01 Sagittarius 06,55'19" Nov 23 6.52 497
Ophiuchus 07,21:20 Sagittarius 18,36'01" Nov 30 18.31 948
Sagittarius 25,57:21 Sagittarius 33,24'25' Dec 18 32.55 867
NOTE: The Sun passes 8'57" inside the North-East border of the Constellation Cetus (The Whale) the 28th of March, at zodiacal longitude 6:50:13 of Aries (in 1979). This table was made by the author with data provided by Pierre Bachus in "L'Astronomie" June 1979, pp.297-99.


Having overviewed the 4 different cycles or zodiacs that enter the picture, what is left is to determine the relationships they have among themselves, as we saw, in terms of starting point (normally the Aries 0 point), manner of division (equal signs or unequal constellations), and speed of rotation.

From the astronomical perspective, the basic relationship is that between the tropical and the sidereal zodiac, usually assumed to mean the passing of the vernal point backwards through the zodiacal constellations, giving origin to the so-called astrological eras. Traditionally, the eras are assumed to be of equal length, but this is more based on tradition than astronomy, since in terms of what is seen in the sky, the constellations are all of unequal length.

The speed of rotation of the moving tropical zodiac with respect to the fixed sidereal zodiac is 30 degrees per 2148 years. This value is only at present, since strictly the velocity accelerates and decelerates with a period of 41,000 years, in consonance with the period of oscillation of the obliquity of the ecliptic, and this produces a variation between 2054 and 2226 years.

The equinoctial and solstitial points of the tropical zodiac can be readily ascertained mathematically, but where do we put the measuring stick of the sidereal zodiac? This is a historical problem, consisting in determining where was the zero point of the sidereal zodiac used in antiquity, since the ancients, based on a direct relationship with the nocturnal sky, never bothered to work with tropical positions. It has been demonstrated (or is a matter of controversy) that the Babylonians before the Greeks were aware of the precession of the equinoxes, but they never abandoned their sidereal reference frame.

One important fact is that the Babylonian zodiac, as far as historical research can tell, was always of equal 30-degree divisions. In India today, astrologers use sidereal signs (not constellations), because their practice derives from Babylonia via the Persians and the Greeks. But there are different traditions or "schools" based on different ancient authorities or "canons", each with a different starting point. The difference between the equinoctial zero point (0 Aries in the tropical zodiac) and the zero point of the sidereal zodiac varies slowly with time at a rate of 1 degree per 71.6 years, and is called the "Ayanamsa", a term adopted today by western sidereal astrologers. But there are different "ayanamsas" in use, according to school or tradition, varying from 21 to 26 degrees at present.

Western astrologers, by means of historical research on Babylonian practices and empirical statistics, use an ayanamsa of about 24 degrees based on a starting zero point called the Fagan-Bradley "synetic vernal point", which determines where the Spring equinox falls in the traditional sidereal zodiac of the ancients. This reference point, adopted for example by Robert Powell, is today in 5d16' 25.6" of the sidereal sign of Pisces, which means that, for the astrological "Era of Pisces" to end, there are still 377.6 years to go, or, in other words, the "Era of Aquarius" will be starting in the year 2377.

But let's not forget that the above date refers to the traditional signs used by the ancient Babylonians, and not the modern division line established by the IAU in 1928. Using this international conventional line, the "Era of Aquarius" will start in the year 2597, corresponding to the vernal point reaching the modern Pisces/Aquarius border.

This, presumably, is why 2626 AD has been mentioned mistakenly as the beginning of Steiner's 6th cultural epoch, but Steiner's cultural epochs have little to do with this. How they are related to the astronomical facts outlined here will be the subject of another message, which I hope will be the last, so you won't have to endure these technical questions much longer.


We have seen that, according to the approximate starting point of the ancient Babylonian zodiac, the shift from the sidereal sign of Pisces to the sidereal sign of Aquarius will happen in 2377 AD (the exact date in the Fagan/Bradley zodiac is June 16 2376). According to the modern definition of constellation boundaries, the date is May 22, 2597. Going backwards, one finds that, in the ancient Babylonian zodiac approximation of Fagan/Bradley, the shift from Aries to Pisces happened in 9 September AD 221, making 2155 years the time it takes the vernal point to travel 30 degrees of the zodiac. The difference of 2155 years seems to be closer to the traditional number mentioned, 2160, used by Steiner, but the correspondence disappears when one calculates how much it took to travel 30 degrees before that, when the shift was between Taurus and Aries: this happened in the year 1954 BC, so the duration was 2175 years:

If we call the Fagan/Bradley "Synetic Vernal Point" the "Zero Point" of the Babylonian Zodiac, the duration of the exact 30-degree Eras would be:

Taurus   = 4145 BC to 1954 BC
duration = 2191 yrs

Aries    = 1954 BC to  221 AD
duration = 2175 yrs

Pisces   =  221 AD to 2376 AD
duration = 2155 yrs

Aquarius = 2376 AD to 4510 AD
duration = 2134 yrs

We also have to understand that these are sign boundaries, not constellation boundaries. The modern boundary between the unequal constellations of Aries (24,44 degrees) and Pisces (36,44 degrees) was reached by the vernal equinox around the year 68 BC, while the boundary between the constellations of Taurus (36,43 degrees) and Aries was reached by the vernal point around 1864 BC. However, actual unequal constellation boundaries are never used in the tradition of the astrological eras, which is based on sections of 30 degrees each, therefore only roughly based on what is really seen in the sky.

Steiner mentions the year 747 BC as the start of the 4th cultural epoch, which he relates to the constellation of Aries, and 1413 to the start of the 5th cultural epoch, which he relates to the constellation of Pisces. He also mentions 333 AD as the midpoint of the 4th epoch.

Several conclusions can be drawn from this:

a- He is using a period of 2160 years for each epoch, 25920 years for the whole cycle. Therefore he is following tradition, and only roughly astronomy.

b- He confuses the unequal zodiacal constellations observed in the heavens with the equal sidereal zodiacal signs of astrological tradition.

c- The dates he mentions, do not correspond, by any means, to the start of a constellation, or of a sign, but correspond roughly to the middle of a sidereal sign. 

The three conclusions above are, of course, from a physical, and maybe etherical, point of view. There could be "occult", "astral", "clairvoyant" reasons or explanations why Steiner defined the cultural epochs as related to the "constellations" the way he did, but astronomically --or physically-- one must not get confused.

The ancient Babylonian zodiac , as we saw, places the start of the Era of Pisces around 221 AD, while the Indian tradition places it around 400-650 AD; Steiner mentions the year 333 AD as the middle of the 4th, rational soul epoch. The relationship is evident, and it means that:

a- the start of a cultural epoch is the midpoint of the astrological era.

b- he is using a zodiac with a starting point which is 1,33 degrees away from the traditional zodiac of antiquity

c- 333 + 2160 = 2493 is the summit, the acme of the 5th cultural epoch, which corresponds very clearly, albeit roughly, to the time of entrance of the venal point in the sign (2377 AD) as well as the constellation (2597 AD) of Aquarius.
NOTE: This difference of more than 1000 years for the start of a Steiner cultural epoch, when compared with the traditional doctrine of astrological eras, could also be explained if one assumes that the reference point is taken to be not a hypothetical mathematical "line" where the constellation starts (or at the middle of it), but --roughly-- the time when the constellation can be observed SETTING HELIACALLY at the Spring Equinox. A good reference for this line of inquiry (not directly related to Steiner) is Terry MacKinnell's forum, where I first found this idea.

Juan Antonio Revilla
San Josť, Costa Rica, September 4, 1999.
(revised March 2004 )

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