Astrology – part 1

Just the other day a friend asked me about astrology, and whether it had any scientific merit. She said that she’d read all sorts of astounding claims about the validity of astrology, as well as “scientific proofs” of its efficacy. Well, as far as I can tell, it’s all bunkum, although, as we shall see, it does possibly have a certain psychological palliative value, I think.

The first thing to note is that astrology was invented a very long time ago, when most people believed that the earth was at the centre of the universe, and was orbited by all the other planets, as well as the sun and the other stars. Needless-to-say, this outdated scheme fit very nicely with humankind’s sense of self-importance, a sense that comes out very clearly in the scriptures of many of the world’s religions -in which the creator of the universe puts human beings in the centre of all things. Anyway, this ancient belief is based on what is known as the terra-centric model of the universe (terra = earth, and centric = centred), and, as I’m sure you are all aware, has been conclusively overturned by a series of empirical observations beginning with the work of Nicholaus Copernicus (1473-1543), Tycho Brahe (1546 -1601), Galileo Galilei (1564-1642), Johannes Kepler (1571-1630) and Isaac Newton (1642-1727).

Thus, as you can see, already the model of the universe on which astrological calculations are based is fundamentally wrong. As that weren’t enough, the earth precesses (wobbles) very slowly on its rotational axis, taking about 26,000 years to perform one complete wobble. This precession means that the stellar constellations (groups of stars) which were directly overhead in say spring 3- to 4,000 years ago (more or less when astrology was invented), are not the same constellations that are directly overhead in spring today.

For astrology, what this means is that the ‘houses of the zodiac’ (the constellations through which the sun appears to pass during the course of one year) are no longer where they were 3,000 years ago. They are still in the same order of course, but they no longer rise at the same time of the year as they did when ancient peoples invented astrology.

Now, since the essence of astrology has to do with what house of the zodiac the sun and the planets happens to be in when you were born, and since these ‘houses’ have not been corrected for precession, the result is that the charts today are off by about one and a half houses. At a more personal level, what this means is that if you think you are a Cancer, say, in actuality you are either a Leo, or a Virgo (depending on whether you’re an early Cancerian or a late one).The calculation of how many houses the system is off by is a fairly simple one. There are supposedly 12 zodiacal constellations, and it takes the earth roughly 26,000 years to complete one precessional loop (wobble), so the constellations shift over by roughly one house every 2,000 years 26,000 ÷ 12 = 2,167). Thus, today, roughly 3,000 years after astrology was invented, the charts are off by more or less one and a half houses.

The next problem with astrology is even more damaging to its credibility. Although there are traditionally only 12 zodiacal constellations (the constellations through which the sun appears to pass over the course of one year), in actual fact 13 constellations lie on the plane of the ecliptic (the path that the sun takes on its apparent journey through the stars of our sky).The 13th constellation is Ophiuchus. However, even though more of Ophiuchus lies across the plane of the ecliptic than does Scorpio, Scorpio is included as one of the signs of the zodiac, and Ophiuchus is not. This has to do with some historical problems with establishing constellation boundaries, but this does not detract from another fundamental flaw in astrology: there are actually 13 constellations which lie in the path of the Sun through the sky, and not only that, but the area of the sky occupied by Ophiuchus (which has been there for millions of years by the way) is not some miniscule fraction of the sky: Ophiuchus is a fairly large constellation, and it intrudes quite significantly into the zodiacal constellations; Houston, we really do have a problem!

Incidentally, although the 12 established zodiacal constellations all get an equal share of the year (1 month for each), they don’t all occupy the same area of sky. Thus, the sun actually spends a much longer time within the borders of some of houses of the zodiac (e.g. Virgo), than others (e.g. Scorpio), which is yet another problem for astrology to contend with, since following the strict logic of matters, astrological ‘months’ ought to all be of different lengths. So much for the astronomical problems with astrology. However, this is not where it all ends. There are also physics problems with it, and we will turn to these next time.

For now, keep reading those predictions if you like, but remember to read the predictions for the next two signs as well, just in case!


Jothi's a guy who's inordinately curious about all manner of things, and has been trying to understand the way the world, in all its myriad facets, works, as well as to convey his understanding of this to all and sundry for most of his life. He has tertiary-level academic qualifications in a variety of different fields ranging from the hard sciences, through the social and behavioural sciences, to the humanities. He's willing to try almost anything at least once, and many things more than once.

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