When astrology is tested by science

Is European astrology a science or not?


Dijon, France, Spring 1994 (English translation: November 1998); Last update, June 2010


Christian Nitschelm & Raslan Leguet


I. What is a science?


Science: Corpus of knowledge and studies of an universal value, characterized by an object and by a given method and based on objective relations that can be checked as well as on observations and verifiable repetitive experiments.


Classification of sciences according to their object:

+ Mathematical sciences;

+ Physical sciences (physics, chemistry, astronomy);

+ Earth sciences (geology, paleontology);

+ Life sciences (biology, genetics);

+ Social sciences (anthropology, psychology, study of the human societies, etc.).


Fundamental sciences: Mathematics, astronomy, physics, chemistry, Earth sciences (geology and paleontology).


Sciences proceed from scientific methodology. They progress gradually, by successive experimentations, trials, errors, and callings into question based on doubt and skepticism.


Skepticism: Refusal to admit an assertion or a dogma, especially when they are unverifiable or unfounded, without making a critical examination of it.


II. Astronomy, a full science.



(From the Greek astron: star and nomos: law) Science which studies the relative positions, the movements, the structure and the evolution of the stars. Objects studied by astronomy: in the Solar system: Sun, planets, satellites, asteroids, comets, interplanetary medium; in the Galaxy: stars, cluster of stars, nebulae, interstellar medium; in the Universe: galaxies, quasars, clusters of galaxies, intergalactic medium, as well as the various radiations which bathe the Universe.


Fundamental astronomy:

a) Astrometry = astronomy of position:

Determination of the positions and the movements of the stars. Creation of star catalogues (movement, parallax, double stars, dynamics of the Galaxy, etc.).


b) Celestial mechanics:

Linked to astrometry, it deals with the laws governing the movements of the stars. It involves the creation of astronomical tables (ephemerides) and the calculation of orbits of double stars, planets, comets, asteroids, spacecraft's, etc.



Physical study of the stars through the whole electromagnetic spectrum: gamma, X, ultraviolet ray, visible, infrared, millimetric, radio. Discipline born in the nineteenth century thanks to the appearance of photography and spectroscopy, it has diversified later into various branches (radio-astronomy, space astronomy, etc.). It leads to cosmology and exobiology.


III. False sciences.


False sciences or pseudo-sciences: Doctrines having an esoteric character, deprived of any scientific value, comparable to beliefs or impostures and based on unprovable and unverifiable assertions generally coming from the field of the irrational. The followers of these pseudo-sciences try to make them pass, often virulently, for real sciences.


Occult sciences: Doctrines and secret practices using so-called forces or energies which are recognized neither by science, nor even by religion, and requiring an initiation of a mystical type (alchemy, astrology, cartomancy, magic, necromancy, divination dowsing, telepathy). The so-called occult sciences are undoubtedly classified among pseudo-sciences: they can in no case be classified as true sciences.


False sciences do not proceed from scientific methodology. They use, as far as possible, human credulity with tempting and misleading irrational speeches or even pure and simple impostures.


Credulity: Too great easiness to believe a dogma or an assertion without bases.


Imposture: Action to mislead by untrue speeches, false appearances, which can too easily lead to a swindle.


IV. The case of astrology.


Astrology or, more correctly, astromancy: Art of determining the character and of predicting the destiny of men by the study of so-called astral influences, as well as the position of major planets, aspects and zodiacal signs. Assertion of the existence of a relation not proved scientifically between man and cosmos.


Horoscope: "Which considers the hour of the birth". Study of the destiny of an individual, made by astrologers, based on so-called astral influences which are supposed to exert themselves on him since the hour of his birth by the observation of the state of the sky and the aspects at this time.


The various European astrological schools often have nothing to do with each other as far as their interpretation of astrology is concerned. Alchemical hermeticism, determination of the character or prediction of the future by some process or other, generally completely irrational, tropic astrology against sidereal astrology, the astrological schools clash, sometimes very aggressively. It is thus much more correct to speak of European astrology's or, when referring to etymology, of European astromancy's.


V. When astrology is tested by science.


V.1. Astronomical bases.


The basic astronomical concepts are rather generally very badly assimilated by astrologers, whatever the school they belong to. The concept of constellation, which is a simple subjective appearance without any physical reality, is very badly understood by astrologers. They indeed associate the constellations with strange and unreal properties related to their names. The forms of these constellations, whose names generally result from Greco-Roman mythology and have significantly varied since Antiquity, were fixed only in 1930, as well as their number.


The concept of zodiacal sign, which does not have a meaning any longer in modern astronomy, is even more badly used by astrologers because of a simple ignorance of the apparent movements of the stars and of some peculiar movements of the axis of terrestrial rotation. The apparent trajectory of the Sun in one year around the Earth defines on the celestial sphere a large circle called the ecliptic. The ecliptic thus cuts fourteen constellations, of very unequal sizes, on the celestial sphere with their limits of 1930, in this case Pisces (the Fishes), Cetus (the Sea Monster, which is simply skirted by the ecliptic), Aries (the Ram), Taurus (the Bull), Gemini (The Twins), Cancer (the Crab), Leo (the Lion), Virgo (the Virgin), Libra (the Scales), Scorpius (the Scorpion), Ophiuchus (the Serpent Holder), Sagittarius (the Archer), Capricornus (the Sea Goat) and Aquarius (the Water Bearer). Curiously, astrologers have only kept twelve of them to make the twelve zodiacal signs (all of size equaling 30°) of European astrology.


Furthermore, the number of zodiacal signs has significantly varied from one civilization to another since Antiquity. Indeed, it passed from 6 in primeval Mesopotamia to 28 in medieval China, while passing by 11 at Babylon and 20 for the Toltec's. This simple observation removes any logical and precise significance from the twelve signs used nowadays. Why not, indeed, one, ten, one hundred, three hundred sixty five or ten thousand zodiacal signs? Why an integer of signs? Indeed, the constants used in mathematics, physics, chemistry and astrophysics are generally real, i.e. not whole. Why would the astrological constants be then almost always whole?


Because of one of the movements of the terrestrial axis of rotation, called the precession of the equinoxes, the zodiacal signs slip slowly along the ecliptic circle in the retrograde direction compared to the constellations of the zodiac, looping a complete rotation in 25750 years. The consequence of this slow movement is that the zodiacal signs have stopped corresponding to their associated constellations for a long time. For example, the Sun is not in front of the constellation of Aries towards the end of March, but in front of that of Pisces, not far from the official limit with Aquarius, near the place where the Vernal Point is currently located. We can notice that the Vernal Point is given by the direction of the Sun at the time of the vernal (March) equinox. At that time however, it is supposed to be, according to any astrologer, in the sign of Aries, the Ram. In opposition to this problem, some astrologers practise an astrology known as sidereal, which is opposed to traditional astrology, known as tropic, and which considers the constellations of the zodiac and no longer the astrological signs. This new kind of astrology is immediately classified as invalid, the seasons not corresponding anymore to the position of the Sun...


By a curious use of the phenomenon of precession of the equinoxes, some astrologers oddly assert the existence of ages of astral influences. Thus we would be, according to them, towards the end of the Age of Pisces, not far from the beginning of the Age of Aquarius. In fact, these ages would correspond to the period of crossing of the constellation associated by the Vernal Point, because of the movement of precession of the equinoxes. Each astrologer suggests his own date, each time different, for the beginning of this so-called Age of Aquarius, which would always begin in an immediate future. However, while taking the official limits of 1930 for the zodiacal constellations, one arrives by a simple calculation at quite different dates, the beginning of the so-called Age of Pisces being located towards 70 BC, and its end in year 2614 AD, which completely invalidates the astrological reasoning. The so-called Age of Aquarius, which does not make any sense at all in astronomy, only exists in the too fertile, or even delirious, imagination of these astrologers who seem to mix up their fantasies with reality, the constellations being only fictitious projections of some quite terrestrial myths on the ancient Greeks' vault of heaven.


The position of a star on the celestial sphere can only be perfectly known with a system of three co-ordinates: the celestial longitude brought back to an origin, the celestial latitude and the distance. The ignorance of one of these three co-ordinates leads to an enormous inaccuracy in the position of the star. The ecliptic co-ordinates constitute one of the principal celestial frames of reference used in astronomy. The astrologers use very badly this system, the ecliptic longitude being the only one taken into account by them in a very vague way. The knowledge of the precise position of a star is incompatible with the astrological system of location.


Astrology is a product of the temperate areas of the Northern Hemisphere. Indeed, it is only suited to these areas, would it only be because of the phenomenon of the seasons. In the temperate areas of the Southern Hemisphere, the seasons are reversed, which removes any likelihood to the associated symbolism. Thus, the sign of the Lion, which corresponds to the boreal summer, is supposed to have properties of exhalation of heat, which of course does not work in the other hemisphere, which is then in full southern winter. In the tropical zone, the situation is still worse from an astrological point of view, the seasons being only two, the dry season and the wet season (prone to regional variations), without variation in temperature!


In the polar areas, the majority of the astrological systems in use do not even make it possible to build viable horoscopes. Some stars and some signs are indeed never visible there, whereas the astrological "houses", which are absolutely essential for the development of the horoscope, cannot be calculated any longer and do not cross any longer, anyway, the ecliptic, in the majority of the cases.


What is, on this subject, the physical significance of the astrological "houses" and why can they not exist in some cases on and beyond the polar circles? Indeed, these astrological "houses", wherever one is in the Universe, correspond to nothing at all! From another point of view, if astrology were a science, one can legitimately wonder what the horoscope of an individual born elsewhere than on Earth would be, the laws of physics being the same everywhere in the Universe.


What then would the influence of the Earth be?


V.2. The laws of physics.


Astrology implicitly presupposes the existence of a certain number of astral influences due to the Sun, the Moon and some other objects, in this case, the large planets. If there are astral influences, then coherent laws giving their natures, their ranges, their modes of action, as well as their factors of dependence (distances, masses, electric charges, etc.), have first to be worked out. Indeed, one should expect a kind of physical law in function of distance d, mass m, electric charge q, ... of the disruptive celestial body, according to a formula like F = a f(d, m, q, ...) = a dα mβ qγ ..., where a would be a factor independent of the disruptive heavenly body and where the exponents α, β, γ, ... would be positive or negative real numbers.


Are these so-called influences forces? If so, of which type? Only four types of fundamental forces are currently known: strong interaction, weak interaction, electromagnetic interaction and gravitational force. In which type of fundamental force is it possible to classify these astral influences? Are they a new fundamental force? Then it would have to be defined! From another point of view, if these influences are not forces, then are they energies? If so, the same question arises, as energy is perfectly quantifiable! Many forms of energy are known: kinetic, potential, elastic, radiative, chemical, nuclear, internal, etc. Which can be the form of energy which could correspond to the so-called astral influences put forward by astrology?


Then, what is the nature of the astral influences presupposed by astrology which would act on the individuals at the moment of their birth (why not the moment of their conception (would this be an indiscretion?) or any other moment?)? How would these influences act on the humans (and why only on the humans?) or on some individuals (in Babylon, only the prince, who was himself a demigod, was judged worthy to be in relation to the "god-stars"). What are the physical laws, which govern these so-called astral influences and how do they evolve according to the distances, the masses or other parameters? Why could close bodies (people, buildings, cars, trees, etc.) not act as much, or even more, than the planets or even than some brilliant stars, because of proximity (case of gravitational and tidal forces)? Why, on the contrary, could very distant bodies (stars, galaxies, galaxy clusters...) not act in the same way, only because of their great number (case of a force independent from the distance, presupposed by the astrological vagueness and from which one still awaits a coherent definition)? In addition, what to say of other bodies present in the Solar system (asteroids, comets, natural and artificial satellites, interplanetary dust, radiation, etc.)?


It would thus be necessary to explain clearly why these astral influences would only exist for the Sun, the Moon and some planets, whereas the immense majority of the celestial bodies would not act at all on the human beings. In the same way, it would have to be specified if these so-called influences only act on the human beings (and then, why?) or also on the animals and the plants (and then, how?).


A clear response to this problem was never given. Any scientific experiment worthy of the name has indeed never confirmed the so-called astral influences, which are neither forces, nor energies.


V.3. Statistical studies.


Statistical studies undertaken in an objective and honest way always showed that astrology only worked by pure coincidence and that the signs or planets did not have a particular influence on the destiny of an individual. For example, a statistical study was very seriously carried out in 1985 in California, United States, with the agreement of forty astrologers, among the most famous. This study, which used a series of double blind tests (Carlson, S.: December 1985, "A double blind test of astrology", Nature, 318, 419-425), clearly showed in an objective way that the predictions of the astrologers only work, at the best, by pure coincidence or are, at the worst, completely erroneous: the correlation asserted and/or predicted between the position of the planets and other astronomical objects at the hour of the birth and the personality of an individual does not exist. Clearly, the scientific experiment refutes the astrological assumption.


However, some statistics, which are too far away from impartiality, or even knowingly distorted, could sometimes show the opposite. After analysis, it was always shown that these statistics had been arranged, even falsified, in order to reach such a result. We are far from the honesty and the objectivity of any correctly carried out scientific process...


V.4. Ethics.


What gives the astrologers the right to run the life of other humans? If astrology only defined an ordinary psychological profile, it would already enter in conflict with scientific psychology but would not be dangerous. However, the current evolution of a kind of astrology towards a more or less complete intervention in the life of the individual is completely inadmissible and intolerable, even dangerous, as a number of astrologers substitute themselves, in an absolutely illegal way, for psychologists, medical doctors, or even therapists.


Some astrological practices, which are too much promoted through the media, violate the elementary bases of ethics. Would you accept that somebody you do not known claimed to know you completely and gave himself the right to lead your life in an arbitrary way, for better or for worse? Even if, for most of astrologers, "the heavenly bodies are inclining, but not determining", the astrological determinism, partial or absolute, is clearly opposed here to the free will, which is the inalienable right of each human having lived or living on our planet. Astrology is thus, in a doctrinal way, much too deterministic, as it reduces the free will of each human being. As well, this observation led various churches, in particular the Catholic Church, to reject any credibility to any kind of astrology, as the determinism, even astrological, is contrary to the religious concept of free choice for the salvation of each individual.


The use of astrology for recruitment by some industrial and commercial companies, which is currently illegal, violates the fundamental principles of the human rights. This indeed recalls in a most unpleasant way some of the shameful practices applied during the Occupation, the darkest period of French history. Astrology is also far too often used by some sects, the major goal of which is the total control of the human being and of his spirit by an omnipotent guru.


VI. Conclusion.


Astrology, which has been built since its origin on completely irrational bases, is thus undoubtedly classified among the false sciences and cannot in any case be classified as a real science. Indeed, it remains completely inadmissible in a scientific vision of the Universe for a great number of reasons: divergences between astrologers, hazardous and often unverifiable nature of astrological predictions, vague nature of the so-called astral influences, etc.


Since Antiquity, the astrological vision of the world has always remained ossified, even "limed", in a purely Aristotelian geocentricism, which is in total contradiction with the modern vision of the Universe. This simple observation removes any scientific validity and any credibility from a construction based on an ancient and medieval cosmological vision which is completely obsolete, and which placed the Earth at the center of a hypothetical finite universe of a small size, as well as on a so-called privileged position of the Man in the cosmos. Indeed, the Sun, no more than the Earth, does not occupy the center of the Universe at all. It belongs to our Milky Way, gigantic stellar system of more than two hundred billion stars, of which it does not occupy the center at all. The Galaxy is only one of the billion galaxies and is certainly not located at the center of the Universe. Now one cannot even speak any longer of a center for it!


In 1666, Jean-Baptiste Colbert, who was then the Prime Minister of King Louis XIV, banned from University of Paris the teaching of astrology. It then lost any potential access to the status of science, a status which was still possible to allot to it by error before this date in spite of the very numerous false predictions and those that never came to pass that many of the most famous astrologers had asserted as the Gospel truth from Antiquity to the Renaissance...


The realm of fantasy induced by astronomy is extraordinary. Who indeed does not wonder about the meaning of the World when he/she raises his/her eyes towards the celestial wonders? This question is absolutely legitimate but does not have to mask the fact that the answers remain very complex, and belong primarily to the field of science and philosophy. Astrology gives an answer, which is certainly pleasant, but which is far too simplistic and should in no case satisfy the honest man. Is not astronomy enough to reveal the mysteries of our Universe and does it not implicitly show the vanity of any astrological and divinatory explanation of the World?


As long as astrology is confined to the level of the myth, its existence or its non-existence does not interfere, in any case, with the field of sciences. Scientists do not feel concerned by what appears in fact like a resurgence of the Greco-Roman religion after more than seventeen centuries of Christianity. However, any aspiration of astrology to be recognized as a science remains and will remain inadmissible and unacceptable for the whole of the scientific community as long as the great fundamental questions will remain unanswered!


Why, then, do some astrologers nonsensically seek to make their assertions pass for scientific fact? Are the bases of astrology not sufficiently solid to be able to answer the evolution of knowledge? Is it not here the search for an exorbitant scientific guarantee for a practice very distant from any science, too often close to imposture with a not very avowable aim and, at best, meanly mercantile? Astrology, whatever the school or faction, can in no case claim to be a science.


A classical argumentation against the astrological dogma:

Comparative actions of gravitational and tidal forces


For learning a little bit more about this subject

A Skeptic's View of Astrology
Horoscopes Versus Telescopes: A Focus on Astrology
Your Astrology Defense Kit (Andrew Fraknoi)
Concepts of modern astrology: All are problematic (Ivan W. Kelly)
IAU Symposium 260, Unesco, January 2009 (Philippe Zarka)
Astronomy & Astrology, "Beyond International Year of Astronomy" (Philippe Zarka)

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This document was carried out by Christian Nitschelm