ASTOP: Astrology

Pseudoscience Fact Sheets. In the late 1980s scientists associated with the Austin Society to Oppose Pseudoscience (ASTOP) created a collection of fact sheets on various pseudoscience topics. ICSA (then known as American Family Foundation) received permission to distribute these for educational purposes.

Complete list of fact sheets.

In its modern guise, astrology is based on the assertion that the apparent positions of certain objects in the solar system at the time an individual is born are somehow correlated with his or her personality, activities, preferences and even major life events -- accidents, marriages, divorces, etc. The "stars" (usually only the sun, the earth's moon, and the five planets known in antiquity: Mercury, Venus, Mars, Jupiter and Saturn) determine the best day to ask your boss for a raise, go to the dentist, or take a laxative. There is no agreement whatsoever among astrologers as to how or why this can be. Nor is there any agreement as to precisely what planetary positions lead to which specific traits or experiences. It is almost certain that no two astrologers will "cast" the same individual's horoscope with the same -- or even a similar -- result. The descriptions and situations that do result are generally so vague that they apply to nearly everyone alive on earth at present, so that meaningful verification is an impossibility. How did such a belief get imbedded in our so-called scientific culture?

Astrology is best understood by learning how it began. Astrology is unquestionably the oldest and at the same time currently the most popular of all pseudosciences. The origins of astrology can be traced back 3,000 years, to ancient Babylonia. The existence of large cities depends on efficient and reliable agriculture, and therefore on an accurate calendar, so that farmers know when to plant, when to harvest, etc. The astronomical observations required to construct a calendar and maintain its accuracy were the task of Babylonia's priesthood. Since the observers were priests, it seems natural that their names for the objects in the sky they found most useful for calendar purposes corresponded to the names of the immortal gods in the Babylonian pantheon. We still use these god-names for the planets, although our names (Mars, Venus, Jupiter, etc.) are for the Roman counterparts of the Babylonian gods (Nergal, Ishtar, Marduk, etc.). It was not just a matter of easy-to-remember names: the planets, in some sense, were the gods they were named for.

This odd blend of astronomy and religion led, by about 1,000 BC, to an extensive literature of "planetary omens." Since Nergal (Mars) was the god of wars and bloody battle, a summer in which Nergal shown down brightly from the sky was a good time to wage war (or a time in which risk of war was great). Since Ishtar (Venus) was the goddess of sexual love, a spring night in which Ishtar hung high in the west after sunset was a good time to proposition your girlfriend, chase the new slave around the bed, etc.

By about 600 BC the Babylonians had devised the twelve-sign zodiac: markers in the sky along the ecliptic, the apparent path along which the sun, moon, and five naked-eye planets -- Mercury, Venus, Mars, Jupiter and Saturn -- move in the sky. The "horoscope," a crude chart of the positions of the planets along the zodiac at a given moment of time, was devised soon after. The oldest known horoscope was made for April 29, 410 BC. During the classical era dominated by first Greece and then Rome, Babylonian astrologers (called "Chaldeans") set up shop in most of the large urban areas throughout the civilized world. Greek astronomers scoffed at the Chaldean cults as a ludicrous combination of primitive astronomy and primitive religion, but to no avail -- the Greek and later the Roman public embraced astrology as lovingly as they embraced most of the other bizarre and barbaric cults that wandered to the Mediterranean looking for converts. That astrology makes no sense with its Babylonian religious underpinnings removed was apparent to thinking people from the very first. Roman statesman Marcus Tullius Cicero wrote, in 44 BC, a devastating critique of astrology, which is well worth reading today. Among the points made by Cicero was that no one sees or expects any correlation between the weather conditions at the time of birth of a child and the child's later personality or fortunes. Yet clearly the weather -- extreme cold or heavy rain or harsh heat -- has far more effect on a living thing than dim lights in the night sky. And even if all children born in December were similar in some way -- which they are not -- how would an astrologer know that these similarities were not due to the weather, due to all the children being born into a cold environment, rather than to the sun being in "Sagittarius," or whatever?

However, with the coming of Christianity, the Chaldeans indeed had very hard going. During the early Middle Ages, astrology became essentially extinct in Europe, though kept alive by Islamic scholars. The Crusades brought the heritage of Greek and Roman culture back to Europe and astrology tagged along, co-existing uneasily with Christianity until the dawn of the age of science. The explosive growth of scientific astronomy from 1600 AD onward paralleled a steady decline in the public interest in astrology. By the end of the 19th Century, a French encyclopedia could accurately describe astrology as a vanishing cult with no young adherents.

But astrology made its strongest comeback in all of history in the early 1930s when British astrologer R. H. Naylor invented the daily newspaper horoscope column. Soon every newspaper had such a column and every town several practicing astrologers. The paradoxical result is that the heyday of astrology was not during the benighted Middle Ages, when the average person was sunk deep in ignorance and superstition, and kept there by illiteracy and the rarity of books. Rather, astrology's peak popularity comes at a time when most citizens presumably know the basic facts of astronomy, and are well aware from space-probe photos in the daily newspapers and on TV that the other planets are worlds more or less similar to the earth, and not mystical god-fires in the sky.

At the present time, at least 90% of all Americans under 30 are said to know their "sun-sign." How many know their blood type? Or the name of the Secretary of State? Or Newton's Three Laws of Motion?

Scientists have been quite baffled by the popularity of astrology during the 20th Century, and dozens of careful studies have been carried out to see if there is any actual correlation between the positions of the planets at an individual's birth, and any attribute of the individual in later life. NO statistically valid study has ever shown ANY connection, relation or correlation that would give ANY support to ANY part of astrology. There is no scientific question, there is no scientific controversy, concerning astrology -- it definitely does NOT work.

Why, then, is astrology the most popular of all the pseudosciences? Before turning to this question, let us look more closely at the actual procedures by which the dogmas of astrology generate individual predictions. In order to go from an individual's horoscope, which strictly speaking is just a crude chart of the heavens at the time of the individual's birth, to specific predictions or statements about the individual, the astrologer must consult a table. This table says something like, "Sun in Pisces at birth = individual is a good dancer, has strong feminine characteristics," etc., etc., etc. Now, where did this table come from? (Note that is such a table, not the horoscope itself, or the procedures for drawing the horoscope chart, that is the "guts" of astrology.) The answer is that such tables are simply made up, up whoever wrote the particular manual of astrology being used! This is why two different astrologers will rarely, if ever, "read" the same horoscope the same way. Of course, there are traditional tables, but wherever the table comes from, it is an arbitrary matching of horoscope features to individual characteristics. The predictions are generated randomly, as much as if by throwing dice.

This kind of arbitrariness is characteristic of all pseudosciences, not just astrology. It comes about because the origins of pseudosciences lie not in observations of nature, which anyone can make, and which are "universal" in character -- rather, they lie in accidental historical conventions and cultural traditions. The ancients happened to call the second planet from the sun Venus and the fifth planet from the sun Jupiter. Had they done it just the other way, it would not have made the slightest difference to astronomy, which is concerned with reality -- with the planet itself. Venus would be the big colorfully belted planet with a red spot and many moons. Jupiter would be the nearest planet to earth, hellishly hot. The names would be different, but nothing else, since the names are arbitrary anyway. We could call them "Two" and "Five" if we didn't want to keep the Babylonian-Greek-Roman tradition of gods' names. But note that changing the names would make astrology totally different, because astrology depends only on the names. The "lookup tables" used by astrologers are generally based entirely on word association and suggestions from the names of the things in the horoscope. Thus, Jupiter, chief of the gods, is a leader among gods and men. Venus, goddess of love, rules the emotions. And so on.

Another amusing way to see this arbitrariness is to consider the zodiac, the named divisions of the ecliptic. The Babylonian astrologers, with their heritage of worrying about calendars, sometimes used 12 zodiac signs. But there is no reason for any particular number. The Chinese and Hindus had 28. The Toltec cultures of Middle America had 20. The Babylonians themselves used anywhere from 6 to 18 at various times. The arbitrariness of numbers of signs -- not to mention names of signs -- is obvious. If a given group of stars (unrelated except by the common name!) was given the name "Aries the Ram," this arbitrarily assigned name then predetermines the most popular "interpretations" that are the basis of the tables that astrologers must have … for since rams are aggressive and assertive (in folklore anyway), so will be people born with the sun (or something) "in Aries." How one would distinguish the aggressiveness of the ram from that of the goat Capricorn or the scorpion Scorpio is another problem!

A problem with astrology which was known to Greek astronomers by 150 BC and may have been known even earlier arises from the phenomenon known as the precession of the equinoxes. Because the spin axis of the earth turns in a circle around a direction perpendicular to the plane of the earth's orbit, the point on the earth's orbit at which a given season begins changes slowly but continuously. He problem is that the early astrologers, for whom the sun rose in Aries at the spring equinox, defined the sun sign of Aries to be centered on the equinox. But the equinox swings in a great circle along the zodiac and will not return to Aries for about 26,000 years. Thus today the astrological zodiac sign Aries is nowhere near the actual constellation Aries which gave the sign its name and meaning! No sign matches its constellation now!

Of course, when one has a system based on randomness and arbitrary convention, a shuffle, mix-up or derangement of the system is unimportant, because the whole system is just a random word generator, and it continues to generate random words as you mix it further. The puzzle is how any conscious human being could remain unaware of the arbitrariness of the procedure, once he understands it.

Returning to the question of the popularity of astrology, psychologists have no trouble accounting for it. It comes from the uniquely personal aspect of astrology. Every day you pick up the paper, turn to the astrology column, and read about yourself! Not Ronald Reagan, not Madonna, not Elizabeth Taylor … but you, you, you. It's all about you. It's all to do with you. The whole infinite universe is reduced to dime-store clockwork whose sole purpose is to tell you whether it's a good day to go shopping or not!

Psychologist shave shown over and over that customers are satisfied with astrological predictions as long as there is some ritual of personalization. For example, customers are all given exactly the same vague, general statement. But half the customers are first asked many detailed questions and have to give much personal information before getting the statement. And the other half of the customers are asked for hardly any information at all before getting their (identical) statement. If is invariably found that the first half rate their statements as "very accurate," "very satisfactory," etc., while the second half rate their statements as "all right, but not too precise," or "not as good as some I've had," etc. All astrological readings of all types are invariably so-called "formula readings," vague and general statements that apply to essentially everyone alive, and are in no way specific or individual.

We often refer to the 20th century as the age of science. Modern science has devastated the foundations of astrology at every possible point. For instance, the time of birth of an individual is in no way significant. The individual is formed at conception, 9 months before birth. What are the astrological implications of caesarian sections or induced deliveries? Modern biology has uncovered the molecular basis of genetic inheritance, and there is no room for astrology anywhere in the picture. Molecules don't have horoscopes. From the standpoint of physics and astronomy, astrology is even more ludicrous than from the standpoint of biology and genetics. The gravitational force exerted on a newborn baby by the earth itself is more than a million times greater than that exerted by any celestial object; the tidal stress exerted by the mother and the hospital building are likewise a million times greater than that exerted by any celestial body. The electromagnetic radiation falling on the baby from the hospital room lights is a million times more intense than that from any other celestial object except the sun itself. Most important of all, human beings are made of atoms; everything is made of atoms. If there were any actual phenomenon of nature underlying astrology, everything would be affected, not just human beings. The forces of nature are universal, exerted from atom to atom, and do not discriminate between living and nonliving matter.

In short, there is nothing whatsoever in all of nature as we know it that gives any credibility to any astrological idea. There is nothing whatsoever in astrology itself that gives any credence to any astrological idea. As a belief system astrology is arbitrary and unjustifiable, and has no connection to reality at any point.

An interesting experiment suggested by astronomer Derral Mulholland is to read your newspaper (or any other) daily horoscope "reading" for a week or two, checking it against your daily experience. Then, for the same length of time, read a totally different and supposedly inapplicable "horoscope." You will find no difference in the accuracy, or lack thereof, of the "readings." It seems hardly possible that any thinking human being could take any aspect of astrology seriously, after having had any experience with it. But one should never underestimate the extent of human irrationality.

There are more than 10,000 practicing astrologers in the U.S., and Americans spend more than $200 million annually consulting astrologers. In short, millions of Americans, from Ronald Reagan to minimum wage earners, will doubtless continue to regulate some part of their daily schedule in accord with the arbitrary and potentially harmful "advice" generated by the mindless random-advice generator provided by astrology. Ironically, they will therefore continue to pay unknowing lip service to the tenets of an otherwise forgotten religion of ancient Babylon.

For further reading

The Gemini Syndrome, by R. B. Culver and P. A. Ianna, Prometheus, New York, 1984

Astrology: Sense or Nonsense? by Roy A. Gallant, Doubleday, New York, 1974

"A Double-Blind Test of Astrology," by Shawn Carlson. Nature, Vol. 318, Dec. 5, 1985, pp. 419-425.

"Does Astrology Need to be True? Part 1: A Look at the Real Thing," by Geoffrey Dean. The Skeptical Inquirer, Vol. 11, No. 2, Winter 1986-87, pp. 166-184; "Part 2: The Answer is No," by Geoffrey Dean, The Skeptical Inquirer, Vol. 11, No. 3, Spring 1987, pp. 257-273.


ASTOP -- The Austin Society to Oppose Pseudoscience -- has prepared fact sheets on various topics for the benefit of teachers and others interested in promoting critical thinking. Dr. Rory Coker, Professor of Physics at the University of Texas at Austin, is the author of this fact sheet. The International Cultic Studies Association (ICSA), a professional research and educational organization concerned about the harmful effects of cult involvement, prints and helps distribute these fact sheets. Because ASTOP fact sheets seek to stimulate critical thinking, rather than advance a particular point of view, opinions expressed are those of the authors. A list of available fact sheets can be obtained by contacting ICSA (