What the stars do NOT have in store for you, according to your horoscope

What is your sign? If you can answer that question, you are one of the 90% of adults who know your zodiac sign. This is no surprise: the media, social networks, and digital applications have all recently given a new push to astrology.

In contrast, in a survey conducted in the United States, only 57% of respondents knew their blood type. What makes astrology so special?

Astrology: the study of the stars to read the future

Astrology is defined as the study of the position and movement of the stars as a means of predicting future events and finding out about people’s character. It originated in Babylon around the year 700-450 BC, when the 12 zodiac signs were established – with their interpretation focused on predicting events in the population.

It was in ancient Greece where predictions were transferred to individuals and were made based on the relative position of the stars at the time of birth. For example, the fact that a person is a Gemini means that, at the time of their birth, the Sun (projected in the sky) was in the position that aligned with the Gemini constellation.

The Earth, when revolving around the Sun, makes its way through the different constellations. That path is known as the ecliptic plane. The sun sign, according to astrologers, represents our personality, self-perception, love compatibility, and basic preferences. Thus, studying the position of the celestial bodies can help us choose better friends, suitable love relationships, and make better decisions both professionally and financially.

Three reasons to change your horoscope

There are at least three reasons why your zodiac sign is most likely not what you think.

• The Babylonians observed that there were 13 different constellations on the ecliptic plane; however, since they had a 12-month calendar dictated by the phases of the Moon, they decided to keep that value and used 12 constellations to name the zodiacal signs. The Babylonians deliberately left one out: Ophiuchus.
• All the constellations have different lengths; thus, they are in front of the Sun for variable amounts of time. For example, Leo spans 37 days while Scorpio spans only 7. This leaves many who claim to be Scorpio out of it, among other irregularities.
• Due to the gravitational influence of the Sun and the Moon, the Earth wobbles slightly. Thus, the north pole deviates little by little, producing the precession effect. The result is an apparent change in the position of the constellations. Since the zodiac signs were established around 3,000 years ago, they have now moved about a month. For someone who was born on June 1 three thousand years ago, the Sun would have been in the Gemini constellation. Currently, due to precession, on June 1 the Sun is not in Gemini but instead in the constellation Taurus.

The most famous experiment in astrology: the Naninga Astrotest

In 1996, an experiment was published in which 44 astrologers tried to match the birth data (date, time, and place) of seven anonymous people with their respective personality questionnaires.

The questionnaires were taken from the Berkeley University Personality Profile, and there were other questions also included suggested by the 44 astrologers. Aspects related to education, family, vocation, hobbies, personality, relationships, health, etc. were covered.

The astrologer who managed to correctly match the seven anonymous people’s birth data with their respective questionnaires would win $2,500. The results were disappointing for astrology: the most skilled astrologer had 3 correct matches out of 7, and half of the participants (22) did not have a single correct answer.

There are several articles that put astrology and its predictive power to the test. Spoiler alert: astrology fails every time. An astrologer has the same chances of being right about aspects of our future as anyone else who bases their responses on chance.

There are people who decide on their partner based on the zodiac signs. Nevertheless, it seems that love is not dictated by the stars. A study carried out with 10 million marriages in England and Wales showed that there is no evidence of attraction (or rejection) between the different zodiac signs.

Why astrology convinces so many

Although it is well proven that astrology does not get things right, 27% of Americans and 23% of the French believe in it, while 46% of Mexicans feel that their horoscope is something important in their lives.

Why is that? Astrology is an extremely profitable business. In the United States alone, astrology apps brought in $40 million for their creators in 2019. This makes astrology be promoted even more online, and more and more people are getting into the market.

But the most interesting thing in all this is that humans are prone to errors and biases related with judgement and reasoning. This means that horoscopes fit into our mental mechanisms. Specifically, they rely on what we know as confirmation bias and the Barnum effect.

Confirmation bias shows that prior beliefs and expectations can influence the selection, retention, and evaluation of evidence; that is, we look for information that supports our ideas and ignore information that contradicts them.

For example, if our horoscope mentions that “it will be a day of strong contrasts” and we have a very calm day, we will simply ignore that prediction. However, if we really do have a day of contrasts, the first thing we will think is, “Of course, the horoscope warned me.”

The Barnum effect is a psychological phenomenon that consists of perceiving general and ambiguous descriptions (applicable to everyone) as if they were highly precise statements (made specifically for us).

The horoscope of a serial killer

In 1968, French psychologist Michel Gauquelin published a newspaper ad. In exchange for one’s name, address, date of birth and place of birth, he offered a 10-page personalized horoscope free of charge. A real bargain!

After receiving the horoscope, 94% of those who had sent in their information said they were satisfied with the results, with 90% even stating that their relatives had found the descriptions of their profile to be correct. Where is the catch? They had all received the same text! The horoscope sent out by Michel Gauquelin was that of a serial killer born in France on January 17, 1897.

Horoscopes promise certainty (“our fate is in the stars”). Therefore, it is not surprising that people usually turn to horoscopes in times of great uncertainty. At the height of the COVID-19 pandemic, searches related to horoscopes had their highest peak in years.

The aim of this article is not for people to stop reading horoscopes, because they can be an excellent source of entertainment and fun. Nonetheless, we must emphasize that there is no connection between the position of the stars and our lives.

And although horoscopes seem harmless fun, we must remember that French President Charles de Gaulle, Queen Elizabeth I of England and Indian Prime Minister Indira Gandhi all had astrologers to help them make decisions during their tenures.

Just remember that Cassius said to Brutus (in Julius Caesar, by William Shakespeare):

The fault, dear Brutus, is not in our stars.

– Rappler.com

Yersain Ely Keller de la Rosa is Maestro en Ciencias Bioquímicas, Universidad Nacional Autónoma de México (UNAM).

Kevin Navarrete is Investigador en el laboratorio de Biología Molecular de bacterias patógenas, Instituto de Microbiología, Praga, Czech Academy of Sciences.

This piece was originally published in The Conversation.