Popular Delusions I: Astrology

I do not regularly read the New York Daily News, which could be generously described as a tabloid, but two juxtaposed stories in the May 29 edition happened to catch my attention, and not in a good way. To the right is a scan of the page (click for larger version):

As readers can see for themselves, just below a story on the birth of Brad Pitt and Angelina Jolie’s newborn daughter is an article by the paper’s astrology columnist, Susan Miller, confidently asserting what the girl’s personality characteristics will be based on the date and time of her birth. We are informed that her birth constellation, Gemini, is an “air sign” that will cause her to be “versatile, adaptable, communicative” and that since Jolie is also a Gemini, “mother and daughter will turn out to be very close and share a similar worldview”. Due to the influence of Mercury, the Sun and the Moon, the child “will be a quick learner and will likely have excellent verbal skills at a very early age”.

Astrology is a pseudoscience through and through, a superstition based on credulous notions of magical thinking. Putting an astrology column on the entertainment page, with comic strips and puzzles, is bad enough. But interweaving it with an actual news story, as if it were legitimate information that informed citizens should know about, is inexcusable. (This should not be taken to imply that the frenzied pursuit and harassment of celebrities by paparazzi is a legitimate journalistic endeavor in its own right. If the tabloids want to write a story worth reading, they could instead be discussing Angelina Jolie’s extensive humanitarian and charitable work on behalf of Third World nations.)

The inimitable Skeptico has already provided abundant evidence that astrology doesn’t work, so I will focus on providing some reasons why astrology doesn’t work. For one thing, astrologers speak as if the constellations we see were distinct and fixed objects in their own right, but nothing could be further from the truth. The stars that make up the constellations are of different types, different sizes, different ages, and different distances from each other and from Earth. The only reason they appear to fall into the patterns they do is because of the way they are superimposed from our planet’s vantage point. From a different location in the galaxy, they would seem to fall into a completely different pattern, or no pattern at all. In fact, this will happen: our Sun and our solar system are orbiting the center of the Milky Way galaxy, taking the Earth with them. Due to this motion, in a few tens of thousands of years, the night sky as seen from our planet will appear substantially different, and the current constellations will no longer exist. (The picture below and to the left shows the Big Dipper as it appeared from Earth a million years ago, half a million years ago, and at present; to the right, the Zodiac constellation of Leo as it appears from Earth today and as it will appear from Earth in one million years. The future version could, with sufficient imagination, be seen as a radio telescope. Illustrations from Carl Sagan, Cosmos, p. 197-198.)

And why, for that matter, should these arbitrary arrangements rather than others be significant? The constellations are, without a doubt, highly imaginative interpretations of certain stellar arrangements; they are hardly glaringly obvious patterns in the night sky apparent to all. If I decide that half the stars in Leo and half in Cancer can be put together into a new constellation that affects my life in different ways than either of those two, on what grounds could an astrologer say that this is incorrect? And what about other cultures who see very different constellations than our own?

There is no even vaguely plausible mechanism by which arbitrary arrangements of distant stars could influence the personality traits of human beings here on Earth, much less by which they could do so in such a consistent and predictable way. Vague “gravitational resonances” have sometimes been proposed as the explanation, but this cannot possibly work. For purposes of illustration, take the most massive star known to astronomers, the Pistol Star, which may have as much as 150 times the mass of the Sun. Take, also, the closest star system to Earth, Alpha Centauri, at a distance of about 4 light-years. (One solar mass is about 2 x 1030 kilograms; one light-year is approximately 9.4 x 1015 meters.) Plug these figures into Newton’s law of universal gravitation to determine the gravitational force that a star the size of the Pistol Star at the distance of Alpha Centauri would exert on a 100-kilogram person on Earth:

F = (G * M1 * M2)/r2
G = 6.67300 × 10-11
M1 = 300000000000000000000000000000000
M2 = 100
r = 37600000000000000

This yields a result of 1.4 x 10-9 newtons of force, or in other words, about a billionth of a newton. By comparison, a 1-kilogram object, such as an apple, at a distance of 1 meter from a person exerts a gravitational force of about 6.7 x 10-9 newtons on that person – about five times as much. Another 100-kilogram person standing one meter from you exerts on you a gravitational force of 6.7 x 10-7 newtons, a hundred times as strong as even this example, which is generously slanted to favor the claims of astrology. In reality, the stars making up the constellations are far less massive and far more distant than the numbers used here. Any gravitational force they could exert on us would be utterly negligible and completely swamped by the far more powerful (though still insignificantly tiny) gravitational attractions of nearby objects.

Recognizing that gravity is a non-starter as an explanation, most astrologers simply wave their hands about conveniently undetectable “energies”, deploy extremely garbled understandings of quantum physics, or make naked appeals to magic with principles such as “as above, so below”. These explanations are nothing but modern versions of the ancient and superstitious notion of sympathetic magic, where when two objects are alike or connected in some way, one is assumed to influence the other. (Other classic examples of pseudoscience, such as homeopathy, rely on the same principle.) And while it is true, as astrologers say, that just because we have not yet discovered evidence for such a force does not prove that it does not exist, to claim astrology is valid on this basis is a fallacious attempt at shifting the burden of proof. If astrologers want their beliefs to be accepted as truthful, they should and must provide real evidence, not simply make excuses for why the evidence has not been discovered yet. Whatever the claimed principle is by which astrology works – gravitational resonances, quantum entanglement, synchronicity, harmonic convergences, or just plain magic – can any astrologer demonstrate its existence and efficacy in a well-controlled scientific experiment?

What would have been genuinely impressive would be if astrologers had predicted the existence of large, planetary-sized Kuiper Belt bodies, such as Sedna, Quaoar or the recently discovered 2003 UB313 (alias “Xena”), by recognizing that there were hidden influences on people’s charts not accounted for by known planets. Of course, they did no such thing, and now that genuine scientists have established the existence of these bodies, astrologers are only now eagerly speculating about their possible influences.

Finally, it should not be overlooked that most horoscopes, including Miller’s, include a generous proportion of statements so vague and general as to be nearly impossible to disprove, i.e., Barnum statements. (What person would not “love to travel and learn new things”?) Human confirmation bias does the rest, leading individuals to pick out the elements that seem most applicable to their situation and overlook the rest. Should a horoscope contain some seemingly devastatingly accurate information – and given the millions of different people who read their horoscopes every day, it would be more surprising if this never happened – without a doubt it will be remembered by the recipient; but the far larger number of horoscopes that contain no such relevant information are forgotten. (A similar phenomenon explains religious testimonies supporting the efficacy of prayer.) But in a controlled test where such common errors of reasoning cannot be brought into play, astrology, like other popular delusions, inevitably fails to prove that it is of worth.

Other posts in this series:

About Adam Lee

Adam Lee is an atheist writer and speaker living in New York City. His new novel, Broken Ring, is available in paperback and e-book. Read his full bio, or follow him on Twitter.

  • Philip Thomas

    Of course distant stars have no impact upon us. However, traditional astrology is linked to the date of birth of a given person. Now, while I personally think astrology is bunk, it is possible that babies born in say, Winter as opposed to Summer, have some common trends which could be measured by sociologists or other scientists- some mental health specialists have suggested winter born children are particularly vulnerable to certain mental illnesses. In the Uk, a child’s birthday is determines which year they start school- sometimes down to a few days apart, and there are probably other social constructs like that…

  • Rowan

    Well, fair enough. That’s a reasonable hypothesis. Now what we need for it is some observed evidence and we can start turning the speculation into theory.
    Richard Dawkins wrote an article on astrology in which he compared it to a similarly character-telling “science” – graphology. Unlike astrology, he said, it would be reasonable enough to assume that deducing someone’s character from their handwriting might be possible – and that it was a shame that, as yet, it seemed to be not so. Whereas astrology, by comparison, is just pure superstition – there’s about as much reason to think your horoscope might influence your life as there is to think that the content of restaurant menus in Beijing might.

  • http://dominicself.co.uk Dominic Self

    I was a bit mean the other day – someone read a description of a ‘Gemini’ that was remarkably like me (what a surprise) so I asked what their star sign was. Scorpio, in fact, but I copied and pasted the description from Aries and switched the names around… the inevitable happened.

    Oh wow! What a remarkably accurate description of personality :D

  • Shawn Smith

    On the show that James Randi did for Nova several years back, he went into a college classroom and handed out a bunch of horoscopes for the class, supposedly made for each student individually. He then asked the class to raise their hands if they thought that the horoscope was accurate. Most, if not all, of the class did so. He then asked them to trade their horoscopes with one of their neighbors, and when they did so, and read them, the class realized that they had each gotten the exact same horoscope.

    Even after that demonstration, some of the college students still insisted that just because Randi had this demonstration doesn’t mean it doesn’t work. I’m not sure whether it was because people don’t like to admit they’ve been hoodwinked, or if they are simply completely delusional, or simply misinformed. I know that whenever rationalists try to point this out, we/they are looked upon as the biggest party poopers around and we/they should just shut our/their traps. Bleah. :-þ

  • Philip Thomas

    Well, technically the experiment doesn’t show very much. Imagine if astrology was in fact an accurate discipline. James Randi does the exact same experiment. Nothing changes. The experiment is revealing about people’s credulity, not much else.

    (as I said before, I think astrology is bunkum: but that doesn’t mean you should use poor reasoning to disprove it).

  • Azkyroth

    Well, technically the experiment doesn’t show very much. Imagine if astrology was in fact an accurate discipline. James Randi does the exact same experiment. Nothing changes. The experiment is revealing about people’s credulity, not much else.

    That’s kind of like saying “Just because I’m paranoid doesn’t mean they aren’t out to get me.” Yes, it’s technically true, but if, in a conversation with a person who makes this claim, the former concept can be confirmed, it is more than reasonable to dismiss the latter pending some positive support.

    BTW, where did the spelling “Occam’s Razor” come from, and why do I find myself reflexively using it. Any hypotheses?

  • tobe38

    Have to agree with Azkyroth here. Derren Brown recently did a very similar trick to the one Randi did. It posits a far more plausible explanation for the accuracy with which people credit astrology readings. One quick stroke of Occam’s Razor should render the supernatural explanations redundant.

    Even if people don’t want to admit they’ve been exposed for pride, I think it’s a good exercise to get people thinking critically. It isn’t conclusive proof that astrology is wrong (as with most supernatural claims, it’s barely, if at all falsifiable) but one can only hope that having realised they’ve been bitten once, they’ll be twice shy.

  • Azkyroth

    Actually, it does occur to me that there is one well-established class of influences on human behavior that star alignments could generate: expectancy effects.

  • Philip Thomas

    Ok, I’ll put it another way: Instead of astrology, imagine that there is a detailed psychological profile method developed which claims to predict your actions based on your history and other data. Now, imagine that James Randi comes to a class and hands out identically worded predictions and says they are the result of this psychological profile method (but of course, they aren’t, since the method doesn’t generate identical results over 20 people). James’ predictions are vague enough that everyone says they apply to them: he gets them to swap with their neighbour, and sure enough they have been duped.

    Now, the flaw in this analogy is this: if the psychological profile method has any validity it won’t produce predictions that are that vague: so the students should (if they know about the method) pick up on the fact that their data from Randi doesn’t look like a prediction arrived at using that method. But if they are unaware of the method or have not studied it in any depth, they might be fooled.

  • Quath

    One game I like, which is similar to the Randi game described abobe, is to take a horoscope from the newspaper. Cut them into 12 rectangles without their associated sign. Either remember what they were or keep another paper for reference. Have people pick the best of the 12 descriptions for them. You should find that the person is right 1 out of 12 times.

  • Shawn Smith

    Philip Thomas,

    I agree that James Randi’s demonstration does not prove astrology is bunk, which is the main reason I called it a demonstration, not an experiment. The point I was trying to make, and which I obviously failed to do, was that some people will cling to beliefs that they have invested time and energy, even if the evidence indicates those beliefs have no rational basis. Thank you for your comments–they have demonstrated that I need to work on my communication skills :-).

  • Philip Thomas

    No, I think it was just me being dumb! Rereading your first post its meaning seems perfectly clear now, I guess I should think before posting.

  • lpetrich

    Actually, it’s even worse in some ways. it’s the differential gravitational force or tidal force that is will make a difference, because all the objects being pulled the same amount will not affect their relative configuration. This is easy to estimate for an object with size s and distance r from a mass M:

    F ~ GM/(r+s)^2 – GM/r^2 ~ GMs/r^3

    And using the objects that Ebonmuse used as examples, I find that the star’s tidal force is 5*10^(-18) that of the nearby person.

  • http://blog.atheology.com Rastaban

    One more problem: astrologers don’t even know where the stars are. For example, Brad Pitt and Angelina Jolie’s daugher was born May 27, but Susan Miller identifies “her birth constellation” as Gemini. And yet, on May 27 the sun was not in Gemini but in Taurus. The sun won’t enter Gemini until around June 21.

    Given that astrology is supposed to be about the influence of the stars, you would think that astrologers could at least learn about the precession of the equinoxes and adjust their charts accordingly. (Of course that would presuppose that the actual location of the stars has any astrological importance – which obviously it doesn’t.)

  • http://www.patheos.com/blog/daylightatheism/ Ebonmuse

    Another excellent point. Incidentally, if you ever want to verify which constellation the Sun or any of the planets is in on a given date, I can recommend Stellarium, a free, open-source piece of planetarium software. If you turn on constellation labeling and turn off the atmosphere, it’s clear as day (so to speak) that on May 27, the Sun was indeed right in the middle of Taurus.

  • http://thegreenbelt.blogspot.com/ The Ridger

    The term “Occam’s razor” first appeared in 1852 in the works of Sir William Rowan Hamilton (1805–1865), long after Ockham’s death circa 1349.

    I would guess that it’s used because Rowan thought that was how it was spelled and a lot of his contemporaries picked it up. And that you want to use it because you see it so often. I know I was over 30 before I found out it was Ockham.

  • http://thegreenbelt.blogspot.com/ The Ridger

    Damn. I forgot to attribute my first sentence to Wikipedia…

  • dhagrow

    Stellarium was new to me. Very cool stuff. For those of you interested in similar software:

    • Celestia – Tries to model as much of the universe as it can, including spacecraft and eclipses. Great for getting a sense of scale. Try the in-program demo in the Help menu.
    • NASA World Wind – Just the Earth, but with a lot of different data layers, like hurricane animations or global temperatures.
    • Everyone probably already knows Google Earth.
    • And while I’m at it, Will Wright’s (of SimCity and The Sims fame) upcoming “Life, the Universe, and Everything” simulator: Spore (preview video).

    The first 3 are all free and open-source.

  • http://scienceofgraphology.blogspot.com MD

    Astrology can be compared to Graphology except for the fact that astrology is based more on superstition that science. Richard Dawkins wrote an article on astrology in which he compared it to a similarly character-telling “science” – graphology. <a href="http://ezinearticles.com/?Graphology—A-Science&id=753497"target="_blank"&gt;Graphology can actually be used to identify some character traits where as astrology is based on speculations and superstitions.

  • StaceyJW

    My favorite comment on Astrology when people defend it’s “truth”-

    If it were true that planets influence your personality, and stars chart your fate, wouldn’t the time of conception be much more important than your birthdate/time?
    Birth date is arbitrary in modern times, with induced labor/ ceseareans, etc. If those “forces” were intristically part of your “creation”, wouldn’t it be necessary for them to influence you from the earliest part of your growth? A full term baby is already developed, unlike an embryo.
    Was actual birthdate used because no one understood conception (and could not know when it happened) when Astrology was created?

    Of course, Astrology is not at all LOGICAL- just a bunch of outdated superstition!

  • lpetrich

    As to birth vs. some other point in development; there are numerous such landmarks in development. Conception, hollow ball (blastocyst), embryo disk (embryoblast), implantation, infolding to make gut (gastrulation), infolding to make spinal cord (neurulation), emergence of brain, brain waves, and after birth the ability to recognize oneself in a mirror (18 – 24 months) and the gradual acquisition of language.

    As to astrologers not knowing where the Sun is relative to the stars, that’s because they have not bothered to correct for precession. The “signs” of the Zodiac are located at where their corresponding constellations were about 1850 years ago, when Greek astronomer Claudius Ptolemy wrote his classic treatise on astrology, the Tetrabiblos (“Four Books”).

    Now if astrology was an even halfway rigorous science, astrologers ought to be able to notice the effects of precession on their predictions; they ought to be able to discover a mismatch that can be fixed by moving the vernal equinox appropriately relative to the Zodiac constellations.

    Similar sorts of mismatches were how Neptune and Sirius B were discovered; they were “seen” by their gravitational effects on Uranus and Sirius A well before they were directly observed.