WHY ASTROLOGY DOESN'T MAKE SENSE - PART ONE

Credit: E. Slawik/NOIRLab/NSF/AURA/M. Zamani.

THERE ARE THIRTEEN ZODIAC SIGNS

A few days ago, I was watching a well-known game show on television and one of the contestants mentioned several times that she was passionate about astrology. The host often used expressions such as “studying the stars” or similar, as if astrology were a science.

 As an astrophysicist, I am taking this opportunity to remind everyone that astrology is not a science, but merely a popular belief with no scientific basis. Over the next few days, I will try to write a series of posts to demonstrate why astrology cannot be considered a science. Let's be clear: astrology has been significant in the past for humanity and for astronomy itself.

 Astronomy and astrology share the exact origin, based obviously on the observation of the sky, and thousands of years ago, they were practically the same thing. Then, with the birth of the scientific method, astronomy developed into a science based on data and experiments, while astrology remained anchored to traditions and popular beliefs.

Let's return to the topic of today's post, which is the zodiac signs.

As we all know, there are twelve zodiac signs, which take their names from the constellations through which the Sun passes during its annual movement across the sky. For example, if I were born when the Sun was located within the constellation of Libra, then my zodiac sign is Libra.

Between November 30 and December 17 (approximately), the Sun passes through the constellation of Ophiuchus, which should therefore be considered a zodiac sign, the thirteenth. Don't be surprised if you don't know anyone with the sign of Ophiuchus, simply because this constellation has never been included in the zodiac. And this is not a modern phenomenon, since the constellation Ophiuchus already existed in Babylonian and Greek times (the latter, incidentally, attached great importance to it, associating it with Asclepius, the god of medicine).

The reason why Ophiuchus was never included in the zodiac is purely geometric. Twelve is a nice number, divisible by two, three, four, and six, while thirteen is a prime number, divisible only by one and itself. Furthermore, the celestial vault is 360 degrees long, which is a number divisible by twelve but not by thirteen. For practical reasons, in ancient times, poor Ophiuchus was therefore excluded from the zodiac, keeping the signs at twelve. Although this has been known for hundreds of years, traditional astrology has never felt comfortable including Ophiuchus in the zodiac again.

This alone makes it clear that the zodiac signs are wrong and have no influence on our lives. As if that were not enough, the Sun does not spend the same amount of time within the zodiacal constellations, but takes only seven days to pass through Scorpio, for example, while it remains in Virgo for 45 days. In traditional astrology, again for practical reasons, each sign is associated with a period of about thirty days.

Furthermore, due to a phenomenon known as the precession of the equinoxes, the zodiac signs are now all shifted from the constellations from which they take their names. But we will talk about this in a later post.