By Bruno Macaes

Some people don't leave home without first taking a peek at their sign in the newspaper. Others resort to professional astrologers to guide their decisions for life. Even presidents of the world's most powerful nation, The United States of America, conducted foreign and domestic affairs following astrologers' advice. Indeed astrology seems to be very important in the modern world.

Do you believe in astrology? If you do, surely you are able to explain what astrology is? Yes, OK, astrology describes our personality and predicts our future. But this is what astrology does. What astrology is, really? How astrologers derive their predictions? On what they are basing their horoscopes? What methods they employ?

Many people believe in astrology, even failing to know exactly what it is. Sometimes it's difficult to trace the origins of our beliefs. But why not believing in astrology when even presidents do? Presidents must be highly educated! Besides, astrology is everywhere: there are astrology courses, astrology teachers, astrology books and software. Astrology is in the newspapers. Newspapers wouldn't publish anything false, would they?

I will prove here that astrology is a falsehood, and I hope to convince you!

If you doubt what I say, that's positive. It means you are prudent. Being skeptical is a virtue. Don't accept anything people say. Demand proof. In our case, the proof will be the very definition of astrology, which is absurd, as we will see. It's ironic, though, that as children, we question everything we see, but accept the explanations adults give. After we grow up, we doubt the true explanations, and cling to our beliefs. We tend to believe what, after all, everyone always believed. It's the power of tradition.

Astrology is, indeed, very ancient. Astrological predictions are among the first written documents known. The Sumerians, Egyptians, Greeks and Romans were already practicing it. At that time, as today, there were other means predicting the future besides astrology. You may find it absurd, but the ancients believed that they were also capable of knowing the future by observing bird flight. The practitioners of this type of divination were called augurs. Greek priests believed they could make predictions by observing the guts of a dead animal. Perhaps in the future people will see how absurd tarot cards and astrology are, too.

Astrology is based on a particular myth going back to ancient Mesopotamia and Greece. A myth is a way of making sense of the world, and humans need to comprehend the universe, to feel at home in the universe. That's why myths exist, even though some questions are for a long time beyond man's and women's capacity to answer them. Myths, by the way, originate in the same manner as scientific theories. Both are possible answers to a specific, sometimes existential, problem. The difference between myth and science is that the former consists of fantastic stories, an allegory of impressions accumulated by many generations. There is no need to prove myths. Scientific explanations, in a way, also originate as stories, but scientists seek proof by means of experiments that can be repeated by anyone, anywhere, and at any time. Many hypotheses, of course, fail the tests. Given enough time, those questions answered only by mythology, because they are thought beyond our capacity to investigate them, suddenly become tractable. To our ancestors only four hundred years ago, the problem of the true nature of the heavenly bodies was still a matter of belief. One could (secretly) debate this topic, but it was generally considered unprovable, and mutually incompatible theories were as good as any other. The theory adopted in the Western world was, of course, that of Catholic church. The Earth was flat, fixed and at the center of the world, with the Sun going about it. Today, it's possible to go to Earth orbit and see that it is round and moving.

Astrology is even older than this belief.

When astrology originated, it was a common belief that the skies were perfect and immutable. Stars were lights attached to the crystal celestial sphere. Their positions were always the same. They formed figures, if we mentally united them. These figures were called constellations. The celestial sphere as a whole rotated slowly, and in the course of a year returned to the same position. Five stars were really strange: they seemed to stay still, but as the days passed, it was possible to observe that their position changed relative to other fixed stars. The explanation found was a simple one. Clearly, if five stars move, there must be five additional spheres, one for each star! Closer to us, there were two inner spheres: one for the Moon and the other for the Sun. The moving stars were called planets, from the Greek word for "hikers".

The Sun and planets did not follow disordered trajectories. Curiously, they always followed a line along the same constellations. Even though there were many more constellations in the sky, only twelve were periodically visited by the planets. These twelve constellations were named the zodiac. The first constellation to appear in a year was Aries (the ram), followed by Taurus(the bull), Gemini(the twins), Cancer(the crab), Leo(the lion), Virgo(the virgin), Libra(the balance), Scorpio(the scorpion), Sagittarius(the archer), Capricorn(the goat), Aquarius(the water carrier), Pisces(the fish).

Now we arrive at the important part: the definition of astrology. Astrology is the belief that the passage of the planets in front of constellations has a meaning or significance. Astrologers claim that planetary positions in relation to constellations and one another can tell something about a person's personality or future. In ancient times, such belief was actually understandable. Some stars become visible at specific times of the year, and this was a true signal to start some activities like seeding the soil. But people also believed that the annual return of migratory birds caused the beginning of spring. In pharaonic Egypt, the time of year when the star Sirius, the brightest in the sky, appeared, coincided with the beginning of the annual flood of the river Nile, which fertilized the soil with its humus. It was also summer solstice, the longest day of the year. The Moon also clearly determined the tides (today this phenomenon is well understood in terms of gravitation). Thus, believing in other "influences" from the stars was just an extension of what was commonly observed.

However, to believe in astrology nowadays is to ignore how the world really works, and all the beauty of today's scientific explanations. It's a superstition. Perhaps many people believe in astrology because they don't know this.

Many of the constellations we know today were named during the time of the Greeks. That's why most of them bear names of Greek mythological characters. The southern constellations were named by the great European discoverers of the early sixteenth century, who were the first to see them (after the native peoples, that is). They put on them the names of things very impressive at the time: their navigating instruments. Constellations are just drawings that we create with our imaginations, by uniting the points formed by the stars. The drawings, obviously, are not really there. We can create with the stars any number of drawings we please. Pure imagination will suffice. If constellations were named today, perhaps we would have the Automobile constellation, as well as the Airplane, the Computer, the Television and the Refrigerator. These are our icons. But since we inherited those names given by the Greeks and the navigators, we therefore have, among others, Andromeda and Perseus, in the northern hemisphere, Compass and Octant in the South.

Actually, the stars forming the constellations are not even close to one another. We see them close due to our perspective. But their distances vary enormously. Some are very distant, while others are relatively near.

Planets are big and spherical celestial bodies, like the Earth. The Earth is an ordinary planet. The planets that orbit the Sun form the Solar System. They are still the only ones we can see, though studies of other stars' light indicate that they, too, are accompanied by planets. Planets are worlds like our own. One day we will visit them. Their environments are different from Earth's, but who doesn't imagine that human beings will inhabit some of those worlds in the future?

The orbits of the solar planets are roughly circular, and all those circles are different in size, but are roughly imbedded in the same plane. This plane is called the ecliptic. And as we are inside the ecliptic, from our point of view the trajectories of all the planets in the sky are alike. They follow the same path in the sky, passing in front of the same points.

As we see, there is nothing magical about the planets; nothing ready to tell us something we don't know about ourselves. The same is valid for the constellations, which are nothing else but stars distant from us and from one another; drawings made by imagination. There is nothing to conclude from the passage of a planet in front of a star. It's the same thing as one person passing in front of another. Or an airplane passing in front of a cloud. Or even to put your finger in front of a star. Can you tell anything about the future by doing that? The difference is only the distance involved. The matter forming the planets and stars isn't of a different nature than that forming you or an airplane. They are all formed by the same atoms and chemical substances. By the way, the atoms in us were formed inside stars that exploded, in a process called nuclear fusion. There is no way we can draw conclusions from the passage of a planet in front of a star.

Some people may say their astrologer, or soothsayer, or any professional of the "future", for that matter, makes correct and detailed "predictions". They know some things they weren't told; how can this be so? Well, those prophets are excellent observers. Many times, people unknowingly betray much of their personalities, due to their peculiar manners or to the kinds of possessions they carry. Reading a Sherlock Holmes book gives us an idea of how it works. There are even books teaching how to guess such things correctly. There are many more cases of wrong predictions. Two identical twins, obviously born at the same time and place, may end up having completely different destinies. Astrologers say that the small time difference between births make a difference. If this is so, then why they publish predictions for anyone born within a period of a month, not necessarily the same year, in newspapers? There is an infinite number of excuses for wrong predictions. They may say the newspaper stuff is not "serious". But the truth is that if astrology were so good, it wouldn't be so vague and obscure. Predictions are never precise. They are almost always metaphorical. If the precision of astrology is so great in the case of the twins, why the other predictions can't be made the same way, specifying time, place and reason for future events?

Make the following test: tell a friend that you will read his or her sign in the newspaper, and then read another sign instead. She or he will probably say the paper is correct. Newspaper predictions will meet anyone's expectations. Any sign will do, because the "predictions" are actually just directions that fit anyone's life. "To succeed today you must be more obstinate and work really hard". Who on Earth sometimes doesn't feel that more obstinacy and hard work is necessary?

If astrology is so clearly a lie, why does it still exist? As long as there exists gullible people to be misled, it will thrive. Publications about astrology are much more profitable than those about science (in a newsstand I often go, magazines about astrology, much more numerous, are side by side with those about astronomy. The difference, irritating for astronomy enthusiasts, is not perceived by the salesman. Astrology impresses the layperson with a "scientific" appearance. There is a whole system with "houses", "triplicities", "quadruplicities", "aspects", "eras", and so on. But this is not science. All those astrological entities remind us of aspects and rules of a game, not science. Science is always direct.

Today some questions we used to think were impossible to answer are already answered by science. And phenomena we could never have figured out using common sense were discovered. But there are still many unanswered questions. They are in the realm of belief. Each new answer provided by science pushes the borders of knowledge farther away, but also generates more questions. Even so, one day most questions we can't answer today will be solved in the future. We will probably be able to answer what we are and why things are the way they are. Other problems that we will be temporarily unable to answer will arise. It is now time for humanity to stop attributing every unknown phenomenon to gods, magic, or other supernatural entities. The world science has uncovered is much more interesting than the magic world of our beliefs. And much more beautiful. And proved through experiments. When a problem is hard to solve, we should think about it, and when we think a solution has been found, we must figure out how to prove it to anyone. We can't build a castle with its foundations on air and try to convince others to live inside it. We must try to know the world as it really is.