The three great astronomical cycles

I have previously alluded to the dramatic contrast between the Zodiacal Year of 25,920 common years, which for the hermetic tradition would match a human cycle of four ages, and the length of 4’320,000 years that the Hindu tradition in turn assigns to the cycle of four yugas – a length that might appear to be excessive and even arbitrary at first sight as, unlike the former, bears no relation with any known astronomical cycle. However, I have already noted that the key to this issue would be to consider the latter symbolically, at least in connection with the human proper cycle – i.e. the one of the most recent humanity, or Homo Sapiens Sapiens.

With this in mind, I will endeavor now to bring both ends together and establish the real length of the human cycle thus considered by approaching the problem from a new point of view: that of the so-called Manvantara, or “shift” of Manu (the “Father of Mankind”), an ancient Hindu measure of time that in spite of its being primarily septenary and having a length that, as derived from the texts, would be nearly 72 maha–yugas – which apparently increases the difficulty – actually is for the scholarly, with the exception of those who insist on taking these data literally, identical to what I have described as a single maha–yuga.

In effect, the connection with the duration of the human cycle is obvious: the term Manvantara more precisely means “the shift to a new humanity,” in this case our humanity, apart from the fact that from the related word Manusya, which literally means “mankind”, there derive the Latin humanitas, the German mann, the English man, etc., etc., Man being, on its part, “Mankind” proper, the Universal Father, the Adam of the Nordic legends. On the other hand, it is interesting that in the world history there exist variations of the name, Manu, applied to founders of diverse cultures such as the Egyptian (Menes), the Cretan (Minos) and even the Inca, whose first monarch, Manco Capac, was the head of a lineage which extended over fourteen kings – that is, the same number of Manus appearing in a Brahma’s day. For the rest, it is important to note, as indicated by René Guénon, that a Manu is not a mythic, legendary or historic character but, rather, the “prototype of Man” for any cosmic cycle or state of existence to which he gives his Law.

All this sheds light over one of the most impenetrable issues connected with the cycle of four yugas, i.e. the apparent contradiction between multiple human cycles, on the one hand, and a single human cycle on the other – a problem that was pending solution until now. Now we can say that as concerns at least our planet, it is not accurate to speak of a succession of human cycles but of a great “general” human cycle, that of the present mankind, which encompasses all other human cycles whatever their order or magnitude.

Now, since we are assuming that this “general” human cycle – the length of which we are endeavoring to find out – approximately represents the age of the present human race and not of its more or less remote ancestors, the best course will be to previously determine which astronomical cycles are likely to influence it. The problem identified in such terms, such cycles can only be the following:

(I) The Earth’s eccentricity cycle, which results in ice age cycles that approximately occur every 100,000 years and are separated by interglacial periods of 10,000 years. This cycle, which appears to be the main framework within which the present mankind has evolved on Earth, is produced by the lengthening of our planet’s orbit around the sun, which changes every 90,000 to 100,000 years from a circular shape to a more elliptic one and back to start again. When the orbit is circular, the distribution of heat over the Earth during the year is uniform, and when it is more elliptic the Earth is closer to the sun and therefore warmer at some times of the year, the seasons accentuating on a hemisphere and waning on the other due to the modulating effect of the two cycles that are mentioned below.

(II) The cycle of precession of the equinoxes or Zodiacal Year, the length of which is usually rounded as 26,000 years but, as we know, has traditionally been calculated as 25,920 years. What makes this cycle particularly important as a most likely trigger of the human phenomenon on our planet is the fact that when a half of a wobbling period of the Earth’s axis has elapsed, i.e. after 13,000 years approximately, the seasons become reversed: for example, 10,000 years ago, when the Earth was at its farthest from the Sun, in the northern hemisphere it was summer and not winter, as is today (and vice versa).

(III) The cycle of variation of the Earth’s axis tilt over the course of approximately 40,000 years from a minimum of 21.5 degrees to a maximum 24.5 degrees, a variation that obviously accentuates or moderates the overall effect of the precessional period; currently the angle of tilt is 23.4 degrees and decreasing, thus attenuating the difference between summer and winter.

Acting coordinately, these three great astronomical cycles – named “Milancovitch cycles” after the Yugoslavian astronomer who first studied them – subject the Earth to a very complex astronomical pattern that has produced the ice fluctuations throughout the ages, although out of all three it is the period of precession of the equinoxes the one which, by leveraging the combined effect of the other two, seems to have played the main role in the development of the current earthly humanity. Thus, some scientists estimate that approximately 40,000 years ago, when the southern hemisphere was the nearer one from the Sun, and as ice gravitated on the North, at various places, probably in Central Asia, there appeared tribes united by their need to face the hard geophysical conditions that prevailed at that time; and thirteen thousand years later, when the northern and southern hemispheres exchanged their positions before the Sun, some tribes appeared also in the southern hemisphere.

Approximately 18,000 ago, on the other hand, the Earth began to come out of the last ice age responding to a combination of all three astronomical factors, although the inter-glacial proper period did not commence until approximately 10,000 years ago. Now, there is every reason to believe that this inter-glacial period is about to end, and many scientists claim that within a span of time that may range from a few to a thousand years from now, the Earth will have entered a new ice age of 100,000 years; to trigger the process there will only be required a summer with a very weak solar glow, unable to defrost the Northern hemisphere glaciers. And irrespective of the signs of an imminent catastrophic defrost caused by the so-called “greenhouse effect” – the planet warming caused in turn by the excess of industrial emissions – the predominant view appears to be at best (maybe we should say at worst) that this factor would only lengthen the process.

Be it as it may, at this point it should be obvious that, by interlacing and influencing one another, all three great astronomical cycles exert a decisive impact on the life on Earth, an effect that can at times be beneficial and other times devastating. At times, for example, the end of one of them will match the end of another, which will make it particularly severe. Of course, the scenario is even more complicated, for it includes the effect of other minor cycles such as the so-called “small ice ages” or cycles of very strong winters occurring unexpectedly every 180 years approximately, which are apparently caused by the so-called “planetary synods” – the grouping of all the planets on one side of the sun while the Earth is on the other – which occur every equal number of years approximately; or like those cycles of great solar activity that occur every 11 and 80 years mainly (the 11-year cycle has later on been specified as 11 years and 29 days), which appear to influence markedly on the occurrence of draughts, volcano activity and the shifts in the Earth’s magnetism; or again, like the maximum and minimum solar cycles of 500 years each, mentioned in some recent works, which would have furthered the emergence, by turn, of the great historical civilizations. All this without doubt is an engrossing subject, a study of which would require, however, a lengthy space; so for the moment I will stop here and will be back with more in a few more days.

(First published Qassia Feb 17, 2008)