I will preface this by noting that astrology is a big deal. Sometimes people criticize skeptics for focusing on the harmless crazy fringes. Silly fringe beliefs are things like UFOs, bigfoot, and JFK conspiracies, but astrology is not one of those. It has a section in nearly every newspaper. Think about the wasted time and money implied by that.
When I did research for my post on the physics of precession, I learned two new things that the original media reports got wrong.
I had heard that Ophiuchus should be added to the zodiac because of precession. But this struck me as wrong, because precession does not change the sun's path through the sky, it only affects its timing. So I researched and found that Ophiuchus is technically unrelated to precession. The addition of Ophiuchus is based on the Astronomical Union's conventions for constellation boundaries. The IAU's conventions are arbitrary, but they more reasonably align with the constellations than do the boundaries drawn by astrologers, which don't even account for precession.
It also struck me as strange that professional astrologers would be ignorant of precession, as assumed by the media stories. People who just read their horoscopes may be ignorant, but professional astrologers have probably heard it many times. Professional astrologers also tend to know a lot about the mechanics of observational astronomy, and precession is right up that alley.
So I looked it up and found that most western astrologers consciously use "tropical astrology" which is based on seasons rather than stars. Their problem is not one of ignorance, but one of irrationality. There just isn't any rational basis to think that tropical astrology, is any better than sidereal astrology, is any better than assigning horoscopes randomly.
Therefore, it didn't surprise me when astrologers started "debunking" the story, talking about how they knew about precession all along and simply chose to ignore it. Here is a sample of what they're saying:
The signs of the Zodiac are merely symbols and metaphors that divide the year into 12 different and equal "seasons."The last point about comparing astrology to religion is a good one. It's sometimes said that you can distinguish between skepticism of pseudoscience and skepticism of religion, because religion is all about metaphorical and nonscientific truth. Such a simplistic distinction fails because pseudoscience will also frequently resort to metaphorical and nonscientific truth. Well I don't know about religion (because I have my skeptic hat on now, not my atheist hat), but when astrology does it, it's rubbish.
There is no real ram in the sky when Aries begins on March 21st. Wise ancient women and men chose a Ram to symbolize Aries because it represents the initiation of spring.
Astrology is a system of symbols and metaphors designed to help us connect to the universe, just like the words and metaphors found in the various spiritual texts from around the world.
And here's a writer who is skeptical of astrology, but calls for a more careful criticism.
While I agree with the best skeptics that “astrology is rubbish”, this is because there is no evidence that celestial objects can affect our lives, events and emotions in the way that is claimed, not because practising astrologers don’t understand basic celestial mechanics and positional astronomy.I suppose, in the scheme of things, precession is not a significant piece of evidence against astrology. The real lines of evidence are physics and empirical studies. Although, empirical studies are problematic to cite, especially on a blog. Not only am I too lazy to find and cite such a study, it would take a lot more work to verify that it has good methodology, and even more work to avoid cherry-picking.
So I prefer the line of evidence from physics. There isn't any known force that could possibly allow planets to affect personalities without having a vastly larger affect on things like weather. But people tend to remember the hits, forget the misses, and think that vague and flattering descriptions of themselves are highly accurate. The effects of these biases look an awful lot like astrology.
But even though precession is not the major line of evidence against astrology, I still think it's a good story. Despite being ancient news, it was still interesting enough to bring attention to the question of why we as a society accept this astrology nonsense. Is it because we think that we're influenced by the stars, or by the position of the earth? No, even most astrologers think that's nonsense. Instead astrologers believe in an equally nonsensical system of dividing the seasons into twelve parts, naming each part for a constellation that was not quite behind the sun 3000 years ago, justifying this by giving the names additional symbolic meaning, and then making daily predictions based on people's birthdays.