Science Questions with Surprising Answers
Answers provided by
Dr. Christopher S. Baird

How does astrology work?

Category: Space      Published: March 23, 2013

constellations
Public Domain Image, source: Christopher S. Baird.

Hardened scientists will tell you astrology doesn't work. Believers will tell you it does. Who is right? They are both right. It depends on what you mean by the word "work". Astrology is the belief that the alignment of stars and planets affects every individual's mood, personality, and environment, depending on when he was born. Astrologers print horoscopes in newspapers that are personalized by birth date. These horoscopes make predictions in people's personal lives, describe their personalities, and give them advice; all according to the position of astronomical bodies. A survey conducted by the National Science Foundation found that 41% of respondents believe that astrology is "very scientific" or "sort of scientific". Let us break the original question into two separate, more specific, questions: 1) Does the position of astronomical bodies affect a person's life? 2) Can horoscopes make people feel better? These questions are both very different. Both can be determined scientifically.

Does the position of astronomical bodies affect a person's life (beyond basic weather)?
No. The position and orientation of the sun relative to earth does cause seasons. Anyone who has shoveled snow off his walk in January when he would rather be at the beach can tell you that the astronomical bodies definitely affect our lives. Solar flares cause electromagnetic disturbances on earth that can disrupt satellites and even cause blackouts. The position of the moon causes ocean tides. If you are a fisher, the position of the moon can have a significant effect on your livelihood. The solar wind causes beautiful aurora, and sunlight itself is the main source of energy for our planet. But all of these effects fall under the umbrella of basic weather; not astrology. Astrology purports that astronomical bodies have influence on people's lives beyond basic weather patterns, depending on their birth date. This claim is scientifically false. Numerous scientific studies have disproven that astronomical bodies affect people's lives according to their birth date. For instance, Peter Hartmann and his collaborators studied over 4000 individuals and found no correlation between birth date and personality or intelligence. In one of the most famous experiments, Shawn Carlson had 28 astrologers make predictions and then tested the accuracy of their predictions. Before conducting the experiment, he fine-tuned the method so that various independent scientists agreed the method was scientifically sound, and also so that all of the astrologers agreed the test was fair. As published in Nature, he found that the astrologers could do no better at predicting the future than random chance. These results agree with fundamental science.

Fundamentally, there are four forces of nature: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. If an object affects a person, it must do so by interacting through one of these fundamental forces. For instance, strong acid burns your skin because the electromagnetic fields in the acid pull strongly enough on your skin molecules that they rip apart. A falling rock crushes you because gravity pulls it onto you. A nuclear bomb will vaporize you because of nuclear forces. Each of the fundamental forces can be very strong. The problem is that they all die off with distance. The nuclear forces die off so quickly that they are essentially zero beyond a few nanometers. Electromagnetic forces typically extend from nanometers to kilometers. Sensitive equipment can detect electromagnetic waves (light) from the edge of the observable universe, but that light is exceptionally weak. The gravity of a star technically extends throughout the universe, but its individual effect on the universe does not extend much beyond its solar system.  Because of the effect of distance, the gravitational pull of Polaris on an earth-bound human is weaker than the gravitational pull of a gnat flitting about his head. Similarly, the electromagnetic waves (light) reaching the eye of an earth-bound human from Sirius is dimmer than the light from a firefly flitting by. If the stars and planets really had an effect on humans, then gnats and fireflies would have even more of an effect. Even if the gravity of the planets was strong enough to affect you, an alignment of the planets would not lead you to win the lottery for the simple reason that a literal alignment of the planets never happens in the real world.

Can horoscopes make people feel better?
Yes. But it has nothing to do with the horoscopes being right. Horoscopes make people feel better because of a psychological effect known as the placebo effect. The placebo effect is when the belief in a useless method actually makes a person feel better. It is the belief itself, and not the method, that causes the improvement. The placebo effect has been scientifically verified. If you give pills to ten sick patients containing only water, but tell them it is a powerful new drug that will help them, and then have ten sick patients not take the pills, then over time the patients taking pills will show better health. Because of the placebo effect, a new drug must not just be proven to make patients feel better. It must be proven to perform better than a placebo. In accurate medical experiments, the control group is not a collection of untreated patients. Rather, the control group is a collection of patients receiving a placebo. The placebo effect is the mechanism at work with astrology. Many people believe in astrology. When they read their horoscope and follow its advice, they feel better. But it is the belief itself and not the astrology that is making them feel better. Many pseudo-scientific treatments – from crystal healing to homeopathy – help people through the placebo effect. Believing in a treatment that does not actually do anything may help, but believing in a treatment that does is even better. Sticking to scientifically proven treatments gives you the benefit of the belief and the benefit of the treatment's action. For instance, instead of reading your horoscope each morning, go for a walk. Exercise is proven to be good for body and mind, and your belief in its effect will also help you.

Topics: astrology, astronomy, gravity, horoscope, placebo, placebo effect, sign, stars