How Accurate Are Zodiac Signs? Here's What Science Says

My in-laws always have a newspaper on their coffee table. So, before family dinners, I used to read each person’s horoscope aloud. Cancer for my mother-in-law and brother-in-law, Virgo for my father-in-law, Libra for my sister-in-law, and Pisces for my husband.

If their star sign had a dismal divination, I simply made up a more positive reading. I did these substitutions for over a decade until my family realized I was fictionalizing the forecasts.

But are horoscopes even real? Does having a designated zodiac symbol mean someone will have a specific personality trait? Or a prescribed future?

Scientists have long debated the validity of astrology. In recent years, mass data collection has allowed researchers to determine whether there is any scientific validity to zodiac signs. 

Libras and Virgos might make good friends, but they shouldn’t date. People born under Taurus are stubborn. Geminis are playful. Can it really be that people born under the same star sign share personality traits? A 2017 study in The International Journal of Science in Society sought to find out. 

The study used data from a South African governmental agency in which 65,268 job seekers completed a personality questionnaire as part of their application process. All of the participants completed 12 years of schooling and were literate in English. They took the Basic Traits Inventory (BTI) under the supervision of psychologists.

The researcher picked one birth year to include — 1983. Then, they further narrowed the sample by selecting four birthdates: January 1 (Capricorn, n= 49), March 3 (Pisces, n=48), September 3 (Virgo, n= 36), and September 23 (Libra, n= 39).

The sampling meant there were four groups with distinct star signs and planet alignment. The next question was, did their personality test indicate they also had distinct personality traits? 

The BTI measures five main personality factors — extraversion, neuroticism, conscientiousness, openness to experience, and agreeableness. Each of these factors has multiple facets. Extraversion, for example, tests for gregariousness, positive affectivity, ascendance (meaning the person likes to lead large groups), excitement-seeking, and liveliness.

Neuroticism, in contrast, is about how the person responds negatively to their environment. These facets include anxiety, depression, self-consciousness, and affective stability (meaning they get upset easily).

To say a Gemini is playful would probably mean they scored high under extraversion, particularly the liveliness facet. Or to say a Taurus is stubborn would suggest they scored low under the openness to experience factor.

In the study, the researcher ran statistical analyses to look for similarities between the BTI results and the shared star sign. The researcher also analyzed whether there were distinctions between the BTI results and the various star signs.

The study found no statistical similarities among the people who shared the same star sign. Being a Virgo didn’t mean a person was more likely to share personality traits with other Virgos.

The analysis also found no statistical distinctions across the different star signs. Libras weren’t distinct from Virgos, Pisces, or Capricorns.

The researcher concluded that stereotypes about star signs simply weren’t true and needed to be let go: “This affirms, through scientific investigation, that astrology should be seen for what it is, namely an outmoded, archaic belief system based on mythological assumptions.”

Read More: Why Are People So Into Astrology Right Now?

The researcher was correct when they called astrology an archaic belief system based on mythology. Astrology is indeed an ancient practice.

Scholars don’t agree on precisely when astrology originated, but they agree it is one of the oldest occult sciences. 

Scholars also disagree on where astrology originated. One argument is that astrology originated in Mesopotamia, which is now modern-day Iraq. Evidence shows that ancient Egyptians also mapped out the star positions as early as the 13th century B.C.E.

The two approaches were introduced during the 6th century when Persian conquests brought Babylonian astrological ideas to Egypt. 

Traditional astrology has four components. Mundane, or world-related, tried to predict events like harvests, epidemics, or wars. Natal focused on the destiny and character of an individual. Horary posed and answered a question. And elections, which tried to forecast the best day to do something.

Natal astrology is thought to date back to 1300 B.C.E. The oldest surviving birth chart was made for a child born in modern-day Iraq on April 29, 410 B.C.E.

Read More: Who Was Nostradamus and What Did He Predict?

When the ancients mapped the constellations thousands of years ago, they marked the stars as they saw them. Since then, the view has shifted.

Earth is not a perfectly round sphere. There is a bulge near the equator, and so the planet’s axis has a slight wobble. This means Earth shifts backward, and our view changes as the years pass.

But a person can’t simply identify the star sign before theirs and announce that it is their new sign. This is because the creators of the zodiac signs took some liberties when designing the system.

Read More: What Do Astronomers Mean When They Say Mercury Is In Retrograde?

First, as NASA explained in a 2016 blog post — the zodiac signs were always 13, not 12, and the ancients trimmed out Ophiuchus. So, the system people have long followed omitted an entire star sign.

Second, NASA pointed out how the ancients then gave each constellation the same amount of time on the calendar, even though the sun doesn’t point at each constellation for the same amount of time. Whereas the sun points at Virgo for 45 days, it only hits Scorpius for seven days.

For people to truly follow their horoscope, they’d have to do some serious number crunching based on the day they were born — not the ancient calendar. They’d have to include Ophiuchus and the correct number of days the line from Earth through the sun points at the constellation.

Or, they could flip open the newspaper and simply pick the most positive prediction in the day’s horoscope and go with that.

Read More: How Mathematicians Cracked the Zodiac Killer’s Cipher