I have been to astrologers couple of times. Once, whatever he said worked. Not sure if it is a coincidence. Does astrology work?
Dr. Phil Plait, and Astronomer, has a great write up that debunks astrology (I cannot encourage you enough to read that page (or the google cache of it).) Sadly his web page seems to be down, so here’s the Google Cache copy of the same page. After a long discussion and research (with sources), he concludes with
There is no force, known or unknown, that could possibly affect us here on Earth the way astrologers claim. Known forces weaken too fast, letting one source utterly dominate (the Moon for gravity, the Sun for electromagnetism). An unknown force would allow asteroids and extrasolar planets to totally overwhelm the nearby planets.
Astrologers tend to rely on our ability to remember hits and forget misses. Even an accurate prediction may be simple chance.
Study after study has shown that claims and predictions made by astrologers have no merit. They are indistinguishable from chance, which means astrologers cannot claim to have some ability to predict your life's path.
There is harm, real harm, in astrology. It weakens further people's ability to rationally look at the world, an ability we need now more than ever.
Now let's look at other places.
If you want to look at this scientifically though, the first questions to ask: By what mechanism does this work? Why are predictions always very vague? And if the questions are specific, why are they no better than cold reading?
Emily Lu from the Palomar observatory (another Astronomy site) makes these great observations.
With the scientific knowledge that we have gained in recent history, there is little reason to place much trust in the notion that the Sun, Moon, or planets will affect your day to day life. Five thoughts:
1) Distances. As anyone who has taken introductory physics should know, the force of gravity goes with the inverse square of the distance... i.e., the further a body is from you, the less it will affect you. Remember how far away Earth is from the Sun, Moon, and planets (hint: MILLIONS of miles). Though the person who delivered you at birth may be much less massive than any celestial body, they are much closer and would certainly affect you more than the positions of the planets.
2) Other influences. For argument’s sake, let’s say that there is some unknown force that far-away celestial bodies do exert. The laws of physics have yet to be completely understood, so I’ll concede that it may be possible that there is something that works independently of distance and might influence the lives of people. But if that force is not distance dependent, why aren’t stars, galaxies, quasars, or black holes included in astrological forecasts?
3) Uranus, Neptune and Pluto. The three outermost planets were only discovered within the past three centuries. How does that work with the claim that astrologers make about the accuracy of their art for previous times?
4) Precession of the Earth. Due to the slight wobbling of the Earth’s axis, the current position of objects in the zodiac circle are no longer consistent with the tenets of astrology set up thousands of years ago. Your "sun sign" is actually currently shifted over by one (i.e., a Leo is really a Cancer).
5) Build me a house of ham. If you’ve thought about the human reproductive process, you know that a baby spends about 9 months gestating in the mother’s womb before it is born. Why, then, does your birth time matter? Shouldn’t it really be the time of conception that would affect who the baby is to become? Or is it that the muscular lining of the mother protects the fetus from all external forces? In that case, shouldn’t a ham enclosure do the trick?
Also, here is an old video from Carl Sagan's Cosmos series that deals with Astrology. Note how he is reading the same astrology sign from multiple papers.
Keep in mind, any sort of "debunking" of this fervent wish by believers will meet with resistance. There will be explanations and rationalizations, but much like any "psychic", there is no distinguishing this from chance, or the art of cold reading (should you be visiting an astrologer). Confirmation bias will do the rest for you.
Also, keep in mind that astrology has tried to legitimize itself in complexity. Thus there is no single one answer or smoking gun that can be used to talk about it. Rather, a myriad of answers are required to fully understand what is going on. The human brain's pattern recognition software is poor in this sense, and that is why people will fall for this.
There are two claims astrologers make. First, that they can use it to predict the future: Google
Second, that your zodiac sign and date of birth tell something about your character.
The first claim is so inane that I do not think it needs much debunking. It is a mixture of self-fulfilling prophecies and overly vague statements. And, more often than not, it simply fails. Shouldn't astrologers otherwise be able to foresee natural disasters with astonishing precision? It is noteworthy that a lot of astrologers adhering to the second claim shun the first claim in an attempt to strengthen their credibility.
The second claim is easily debunked in experiment: Here is Derren Brown doing a nice little experiment: http://www.youtube.com/watch?v=haP7Ys9ocTk
In brief: He writes "personal readings" for his test subjects and asks them to rate the accuracy of these readings. His readings get extremely high accuracy ratings (80 - 100 %), but it turns out that he has provided everyone with exactly the same reading. This is because he uses so called Barnum statements, also called the Forer effect (The Wikipedia article has a link to the original work by Forer).
A guy named Shawn Carlson conducted a study, published in Nature on December 5, 1985. Unfortunately, that link is a paywall. There's a description available, unfortunately not as authoritative. Essentially, he let astrologers test themselves, by setting up a test where they would use natal charts to predict peoples' scores on standardized personality tests. He picked thirty astrologers that were considered good by their peers. He appears to have given astrologers every chance to prove themselves right.
As people reading this might guess, the results were indistinguishable from chance.
- No. Astrology doesn't work.
- The links above discuss a scientific investigation of the influence of Mars on sports performance and a discussion of the sTARBABY case. The Zetetic Scholar was set up by one of the founders of CSICOP (Marcello Truzzi) to encourage communication between advocates and counter-advocates of the paranormal. The article includes commentary by IJ Good, Hans Eysenck, Piet Hein Hoebens etc.
- And no. Astrology doesn't work.
It may also be worth pointing out that your familiar "astrological sign" ignores precession so to the extent the question relates to the "popular" astrology of newspapers and so forth, even if there were a mechanism, the predictions would be significantly off-base. I believe that even "serious" astrologers rely on the traditional "houses" and would be subject to the same bad data.