Thursday, January 13, 2011


Glanced at Yahoo! News today and saw this article:

Earth’s ‘wobble’ means your zodiac sign may be wrong

The Yahoo! News article starts out stating: "A Minnesota astronomer confirms what many have suspected: Your horoscope is quite possibly wrong."  A phrase comes to mind - "No shit, Sherlock" since astrology is a bunch of hokum but their point, however, was that the wobble of the Earth's axis means your supposed horoscope sign doesn't correspond to the positions of the astronomical constellations anymore.

Let's throw a little science into this discussion (something news articles never do since they assume everyone's a flaming idiot).  What does it mean to say your sign is Aries anyway?  Well, it started with the ancient Mesopotamian cultures around 3,000 BC who observed the sky each night (easy to do without light pollution and TV in a clear-sky desert climate) and noticed that the Sun, Moon, and planets follow a path through the sky which today we call the ecliptic.  It's the plane of the solar system (they assumed everything orbited the Earth back then while today we know it's the plane in which everything orbits the Sun - except, of course, for our moon).

They then developed 12 constellations roughly evenly spaced on the path of the ecliptic (I say "developed" because there's nothing special about the constellations, they're just random patterns of stars we choose to see as related).  From the perspective of us here on Earth, as the year progresses (as we orbit the Sun) we see the Sun passing through each of the 12 constellations each month.  That's why your horoscope sign is called your Sun sign.  Supposedly, if you're an Aries, the Sun was in the constellation of Aries - in other words, from the Earth's surface, the Sun is in line with the stars which make up the constellation of Aries.

Gravitational forces between the Earth, Sun, and Moon cause the Earth's axis to wobble like a slowing top.  This induces an approximately 26,000 year cycle called the precession.  Since the time the ancient cultures of Mesopotamia developed the ideas of astrology thousands of years ago until today, the dates that the Sun enters each of the zodiacal constellations has shifted.

I was born on April 17 and therefore an Aries according to traditional astrology (March 20 or vernal equinox date to April 20).  But if I use a planetarium program like Stellarium, I see that on April 17, 2011 the Sun is squarely in the constellation of Pisces.

Here's an easy to read explanation if you want a bit more detail (What's your sign? The science behind the zodiac).

As you trace this article back from Yahoo! News (credited to Liz Goodwin), to Time NewsFeed (credited to Megan Friedman), to the Minneapolis Star-Tribune (credited to Bill Ward), you actually see that the original story wasn't that bad.  It was a Minnesota Planetarium Society board member Parke Kunkle talking to a reporter about astrology on what was likely a slow news day.  No problem.  By the time the story went through Time and got to Yahoo! News, it was treated like a new discovery.  The Time NewsFeed article breathlessly claims:

"The field of astrology, which is concerned with horoscopes and the like, felt a major disruption from astronomers, who are concerned with actual stars and planets. The astronomers from the Minnesota Planetarium Society found that because of the moon's gravitational pull on Earth, the alignment of the stars was pushed by about a month."

Problem is, astronomers have known about precession since the time of the ancient Greeks - Hipparchus knew about it around 140 BC!  This is not anything new and certainly no "finding" of the Minnesota Planetarium Society (nor would they claim that!).  It's just sloppy journalism.

So why don't astronomers believe in astrology?  Not because of the precession (although it is good evidence that astrology is bullshit).  Simply because it makes absolutely no sense given our modern knowledge about the universe.  Let's look at the constellation of Aries, the ram.

From left to right, the stars that make up the main part of this constellation are Bharani or 41-Arietis, Hamal or a-Arietis, Sheratan or b-Arietis, and Mesarthim or g1-Arietis.  They are, respectively, about 160, 66, 60, and 204 light years away from Earth.  They are not related to each other in any way.  How the hell could those disparate stars affect us at the moment of our birth just because they're in the same direction as our Sun (and millions of times further away)?  And why our birth date - what if you were a preemie?  Isn't the date of conception more significant?  It just makes no sense.

According to a November-December, 2009 Harris poll, 26% of U.S. adults surveyed believe in astrology (not the 31% incorrectly reported in the Minneapolis Star-Tribute article!).  Not surprising since a 1999 Gallup poll showed that 18% of Americans believe the Sun orbits the Earth (science settled that one about 500 years ago).  A certain percentage of people are completely ignorate of modern science, it's that simple.

It does annoy me, however, that newspapers carry astrology columns every day but rarely write anything about real science (and, when they do, it's usually bullshit like the Yahoo! News article that started me off on this topic today).


  1. Thank you very much for this article. I've been searching the web for a rational point of view on this and have finally found one. I never believed that astrology was the way things were necessarily, and I've known the alignment of the stars has been off for awhile, so naturally I was curious to read up about how this became news. I've always followed what I thought was my sign, and in many cases my horoscopes have been accurate - but in many cases I have not. Reading up on the description of my "new" sign, Scorpio, I realized the traits fit me almost as well as those of Sagittarius, my "old" sign. I started to wonder if the position of the stars actually meant anything, or if it was just our minds tricking us into believing something completely false, as modern psychology shows they are so apt to do.

  2. Hello,

    I found your recent 'Duh' blog while surfing the web in an effort to discover why the recent zodiac story is being treated by the media as if the Minnesota Planetarium just made a new discovery. I've known about the effects of precession since I became interested in astronomy as a teenager, which was a long time ago. When I saw the zodiac story on television today my first thought was; Why are they talking about this like it's news?
    I think you've done a good job of explaining how precession works and also how stories like this get inflated by the media. With your permission, I will forward your 'Duh' blog to some other media websites that need to be enlightened on the subject.


    BTW- I'm partial to your birth date. It happens to mine too. I guess we're both Pisces now. ;)

  3. Considering there is countless if not an infinite supply of stars and constellations, couldn't one argue that no matter how many ' zodiac signs ' there are it would work regardless. Just because one group of ' astronomers 'decided to pick 12 groups of stars equally spaced a part does it make it right? What if this original group of ' astronomers ' decided to choose 6, 15, 20, 30 or whatever number you can fathom, evenly spaced apart throughout the year that all fit in the celestial pattern. Wouldn't they technically still be accurate?

  4. Okay, so nice article on the origins of this medusa of a criticism of astrology - you know, the one that sprouts two heads every time it's cut down and pops up later somewhere else. However, like most critics of astrology, your blog post stills show a true lack of understanding of what astrology is, and I'd be glad to give you the basics, free of charge. I've got a Ph.D. in geography and went on to learn astrology. Besides being the two disciplines that everyone misconstrues (oh, I like rocks and stars, too!) they're also both centered around visual analysis of spatial patterns and symbols, so I guess that's why I like both so much. So, if you'll keep an open mind for a couple minutes, I'll educate you and your readers and let you all make up your mind for yourselves. Just don't dismiss something without even understanding what it's based on, how it works, and what it does - that's hardly a rational attitude, but it's the one that astrologers most often encounter. And it's really not responsible to go publicly slinging around pronouncements, much less dismissals, of things that people from all backgrounds and education levels put their hearts and minds into, if one doesn't know the nature of the thing they're criticising, is it?

  5. So, yes, astrologers have known about precession for as long as astronomers have. But, astrologers don't use the constellations of the zodiac to base their interpretations on. No? No. Some use the individual stars of the constellations, but a vast majority use something called the tropical zodiac, which is based on something much closer and more relevant - the cycle of the seasons. The astrological year begins at the moment of the spring equinox. That is 0 degrees of Aries, a sign of the fire element and cardinal mode. The next sign is a fixed mode sign in the earth element, Taurus. The third is a mutable sign in the element of air, Gemini. When we've completed a cycle of modes - cardinal, fixed, and mutable - we're at the beginning of the next season. Summer begins with the cardinal sign of Cancer, in the water element. We use fire, earth, air, and water all the time in colloquial speech. It's a part of our cultural heritage and something common to most all humans. "he's on fire," "down to earth," "drowning in emotion," and "airhead" are just four really simple examples. The combination of four elements and three modes create the energies of the twelve signs and their characteristics. Each season begins with a cardinal sign, establishes itself with a fixed sign, and wraps up with a mutable sign. Each season is composed of exactly three signs of thirty degrees apiece and they trace the apparent path of the sun through the 360 degrees of the ecliptic as the earth revolves around the sun.

  6. Okay, but what about the variety of people born in those signs? Surely that proves astrology is bunk. Well, yes, it would, if that were all astrology is. The sign of the sun is merely one piece of a natal chart, which is a diagram of the sky above and below when and where a person was born. The Moon, all of the planets, the horizon, Pluto and the other Trans Neptunian objects in the Kuiper belt, maybe Ceres and a few other asteroids, some Centaurs like Chiron and Pholus, and the high point and low points of the ecliptic, not to mention a few other points, like the lunar apogee (calculated three different ways), the nodal axis of the Moon, and the Vertex (which has something to do with a prime vertical and something else I can't remember...) can all be plotted on a chart and they all have a general set of meanings ascribed to them. And the angular relationships between these points on the chart describe how the pieces fit together and that all has meaning, too. I haven't mentioned house systems - they're like zodiac signs in that the natal chart is divided into twelve of them, but they aren't all the same size, and can be calculated in several different ways. A hot point of debate among astrologers is always which house system they like to use. The houses represent areas of life that these symbolic planets do their activities in. So, we've got planets (and the luminaries - Moon and Sun), other objects and a bunch of points in your typical natal chart. They're in signs, which as I said are twelve basic kinds of energy we're all familiar with, and they are also placed in houses, which represent areas of life, going from most to least personal 1 through 12, and all of those things are ascribed meanings as are their interactions with each other. That's a little more complex than just the sign that the sun appears to be in during different times of the year. It's only the non-astrologers who still think that's what astrology is.

  7. So, what's all this based on? Astrology is an analytical, subjective social science - or could be if there were more than a few scientists and academics who bothered to let their imagination wander far enough away from their desks to consider testing out interpretations from large data sets of participants and getting astrologers on board with quantifying their finding and developing general statements about correlations between certain configuration, sign or house placements, and the like and characteristics or events in people's lives. A few of these studies have been done, and generally end up corroborating the usefulness of the discipline. Astrologers, like academics, have professional societies with conferences and research journals, newsletters, and popular publications, as well as ethics committees, certifications, testing, and standards. Not all participate, but we're so much outside the mainstream, it's understandable. I just call it an analytical, intuitive craft. It's foundation is the axiom, "As above, so below." That's the short version, but it philosophically summarizes the only thing one has to take for granted in astrology, which is that the placements of and angular relationships between the things in the heavens can be converted to symbols that mean something down here on earth, within us and within our society. The sky is a map we can use to understand ourselves. Why? Who knows. Do we create it? Perhaps. But not consciously. As above, so below. The things - objects and points - in the sky can be put onto to a map and connected like the players in a drama, using a kind of cosmic protractor (the tropical zodiac, based on the cycle of the seasons) and tradition, experience, and imagination can be applied to translate the literal into the figurative in order to understand something about us - you and me and our world. An imperfect "science" to be sure, but hardly less so than any of the other social sciences.

  8. There are many valid criticisms of astrology from what I hear. But how can we even get to them if we're stuck on questions based in a near complete ignorance of what astrology even is? Take the time to learn the discipline, then approach it with real criticism. I invite you.