Is Astrology Accurate? What the Science Actually Found

By Dana Whitmore · 2026-08-15

Peer-reviewed journal volumes and a printed natal chart side by side on a desk"

Western tropical astrology content here is entertainment and self-reflection. Sign descriptions are traditional symbolic conventions, not scientific claims about a person.

I wanted the receipts, not the sermon.

A skeptic friend and a believer friend were arguing about whether astrology "works," and the search results were useless - debunk pages that never stated the actual study designs, believer pages that never stated the actual results.

So I read the studies myself.

Here is every major test, what it actually did, and what the astrologers said back. Every load-bearing claim carries its citation.

The rebuttals are included and honestly weighted. Nobody gets sneered at.

One scope note: this record concerns western natal astrology. Sidereal and Vedic traditions are a separate subject this series deliberately does not cover.

What Astrology Actually Claims

Before testing something, state what you are testing.

Natal astrology holds that the positions of celestial bodies at the moment of birth map to personality traits and life patterns. It is a traditional symbolic convention - planets and signs carry meanings handed down through centuries of interpretation, not through controlled experiments. The practice traces its origins to about 1300 BCE, with the oldest surviving birth chart dated April 29, 410 BCE.

The testable claim: if your sun sign is Aries, you will show traits the tradition assigns to Aries more often than people born under other signs. If Mars was rising when you were born, that placement says something about how you express anger or ambition. These are statements about correlation - birth date and personality track together - and correlation is something you can test.

What would count as evidence? Astrologers selecting the correct chart for a person more often than chance. Large personality datasets showing zodiac patterns.

Agreement between astrologers reading the same chart.

That is what the tests checked.

Is Astrology a Science? The Checklist, Applied

Science is not just lab coats and p-values. UC Berkeley's Understanding Science project outlines what the scientific method actually requires: testability, reproducibility, self-correction when evidence contradicts a claim.

Astrology does not follow that method. Practitioners do not systematically test predictions, and the tradition has not revised its core claims in response to negative test results (those results are coming). That alone would not settle the question - plenty of useful frameworks are not sciences - but it explains why the scientific community does not treat astrology as one of its own.

In 1975, 186 scientists (some reprints say 192) signed "Objections to Astrology," a statement published in The Humanist. Carl Sagan famously refused to sign. He objected to condemning astrology by declaration rather than by evidence, and he thought the more interesting question was why people believe it - an instinct I share.

So: the evidence. Astrology has failed every controlled test to date.

That phrasing - "not supported by controlled testing to date" - is the careful, honest verdict this article uses throughout. "Disproven" overstates what individual studies can do, and "it works" understates what the record actually shows.

The Landmark Tests: What Was Actually Done

The Carlson Double-Blind Test (Nature, 1985)

Shawn Carlson, then a physicist at UC Berkeley, designed a test that astrologers themselves helped shape. About 30 working astrologers (sources conflict between 28 and 30) participated. Each cast a natal chart for a client they never met, based only on birth data.

Then came the matching task: given three personality profiles - one real, two decoys - pick the profile that belongs to the chart.

Neither the astrologers nor the researchers knew which profile belonged to which person during the matching. The double-blind setup meant no one could nudge the results, even unconsciously.

The astrologers predicted they would match correctly about half the time - one in two. Chance alone would get you one in three.

The result: one in three. Exactly chance.

Carlson's conclusion, printed in Nature: the test "clearly refutes the astrological hypothesis." The study tested 116 clients across multiple trials. It remains the most carefully designed astrology test in the peer-reviewed record.

The Aggregate Record: Meta-Analysis and Agreement

The Carlson test was not alone. A review of the literature through 2003 examined about 40 chart-selection studies involving roughly 700 astrologers and over 1,000 birth charts. Once identifying clues were removed - handwriting, demographic hints - astrologers showed no significant preference for the correct chart.

Agreement between astrologers tells you whether they are reading the same signal or different ones. Across about 25 documented studies, inter-astrologer agreement averaged around 0.1. If two astrologers read your chart independently, their interpretations will overlap about as much as two strangers guessing your personality.

The Very Large Samples

Sometimes you need a bigger net. A 2020 study by Lu and colleagues analyzed personality data from over 100,000 people. No relationship between zodiac sign and personality emerged.

A Swiss study of 3,074 nineteen-year-old men (about half the canton's cohort at the time) tested zodiac signs against the Freiburg Personality Inventory. No correlation.

Clearer Thinking, a research nonprofit, ran a blind test with 152 working astrologers. Participants were asked to match charts to personality descriptions. Chance performance would be 20 percent (matching one out of five correctly).

None of the 152 scored above five correct out of twelve trials. Years of experience showed no effect on accuracy.

One more: an analysis of about ten million couples, reviewed in Psychology Today, found no astrological effect on compatibility or incompatibility. The signs you were born under do not predict whether your relationship thrives or fails.

The test record at a glance

Study Year Design Sample Result Source
Carlson 1985 Double-blind chart-to-profile matching About 30 astrologers, 116 clients 1 in 3 (chance) Carlson, Nature 318(6045):419-425
Chart-selection meta-analysis Through 2003 Review of matching studies About 40 studies, ~700 astrologers, 1,000+ charts No preference for correct chart once clues removed Dean and Kelly review
Inter-astrologer agreement Multiple Agreement across readers About 25 studies Agreement ~0.1 Dean and Kelly review
Lu et al. 2020 Large-N personality correlation Over 100,000 participants No zodiac-personality relationship Lu et al. via Psychology Today
Zurich cohort Publication date unconfirmed FPI personality inventory 3,074 nineteen-year-old men No sign-personality correlation PubMed 969917
Clearer Thinking blind test Date unconfirmed (2010s-2020s) Blind chart-personality matching 152 working astrologers None above 5/12 correct (chance = 20%) ClearerThinking.org

One study, read closely: the Carlson test, annotated

  1. The question: Can astrologers match a natal chart to the correct personality profile of the same person better than chance?
  2. The double-blind: Neither the astrologers nor the researchers knew which chart belonged to which profile during matching. No one could nudge the results.
  3. The stakes the astrologers set themselves: They predicted one-in-two success - 50 percent accuracy.
  4. The sample: About 30 astrologers and 116 clients participated. Charts were cast based on birth data alone.
  5. The result: One in three - exactly what random guessing would produce.
  6. Carlson's own words: The test "clearly refutes the astrological hypothesis."
  7. The 2009 reanalysis: A researcher in the astrological community, Ertel, disputed Carlson's statistics and claimed marginal significance (p = .054 in one test). Mainstream science does not accept the reanalysis - contested methodology, not a reversal.
  8. What one study can and cannot tell you: The Carlson test is rigorous but single. The aggregate record (table above) matters more than any one paper.

The Astrologers' Objections, Taken Seriously

Fairness means citing the rebuttals, not ranking them equal to the peer-reviewed record.

The Ertel Reanalysis of Carlson's Data

In 2009, Suitbert Ertel, a researcher sympathetic to astrology, reanalyzed Carlson's data and claimed to find marginal statistical significance - p-values around .054 in one test and about .037 to .05 in another when pooling first and second choices.

The astrological research community cites this reanalysis as evidence the original conclusion was too harsh.

The mainstream scientific reading stands. Ertel's reanalysis involved contested statistical choices, and marginal p-values in a secondary analysis do not overturn a published null result in Nature. If you are keeping score: one peer-reviewed study in a major journal versus one disputed reanalysis in a specialty publication friendly to astrology.

The Gauquelin Mars Effect

This is the believers' favorite study. In 1955, French researcher Michel Gauquelin claimed a small statistical excess of Mars near the horizon in the birth charts of athletes - a pattern he called the Mars effect.

Independent replications failed. The effect did not hold up under controlled conditions. Mainstream science does not accept it.

But it remains the single most-cited piece of evidence among astrologers who argue the record is not as one-sided as it appears.

That is the honest paragraph believers deserve. The Mars effect is not accepted science, and citing it as though it were is a mistake. But it exists in the historical record, and people asking about the science deserve to know what the other side points to.

A Field Split Over What 'Works' Means

Psychological astrologers have largely dropped predictive claims. They treat the natal chart as a reflection tool - a symbolic mirror for self-exploration, not a diagnostic instrument. Research-oriented astrologers, by contrast, still contest the test record and argue the studies missed what astrology actually does.

Both camps operate under ethics codes.

The American Federation of Astrologers, the National Council for Geocosmic Research, the International Society for Astrological Research, and the Organization for Professional Astrology all prohibit practitioners from giving medical, psychological, financial, or legal advice.

Their codes require referrals when a client's needs fall outside the astrologer's scope.

The field's own rules acknowledge the boundary between symbolic reflection and professional guidance. That boundary matters.

The Mechanism Problem

Scientists reject astrology on two grounds: the evidence and the mechanism.

The evidence you have seen. The mechanism problem is this: no accepted physical force links planetary positions at birth to personality. Gravitational effects from the obstetrician are stronger than gravitational effects from Jupiter.

Electromagnetic proposals do not survive the arithmetic either - the inverse-square law makes distant planets irrelevant compared to the hospital's lighting.

One common confusion: NASA ephemeris data make planetary positions computable to high precision. Calculation precision says nothing about whether the interpretations of those positions track personality. A weather app can tell you the barometric pressure to three decimal places, but that does not mean your mood correlates with it.

The positions are real. The claimed correlation is what the tests checked, and the tests came back negative.

The same reasoning settles a claim this page does not cover in detail: whether a sign shapes how you look. Nobody has tested that one directly, and what the appearance tradition actually claims turns out not to be about your sun sign at all.

Why It Still Feels Accurate: Try It Yourself

Rate how well each statement describes you (0 = not at all, 5 = extremely accurate):

  1. You have a great need for other people to like and admire you. [ 0 1 2 3 4 5 ]
  2. You have a tendency to be critical of yourself. [ 0 1 2 3 4 5 ]
  3. While you have some personality weaknesses, you are generally able to compensate for them. [ 0 1 2 3 4 5 ]
  4. You have considerable unused capacity which you have not turned to your advantage. [ 0 1 2 3 4 5 ]
  5. At times you have serious doubts as to whether you have made the right decision. [ 0 1 2 3 4 5 ]

(After rating, a reveal message would appear):

Your average rating: [calculated] out of 5

You just rated the same personality description that psychologist Bertram Forer gave to every student in his 1948 classroom experiment. Participants rated it 4.26 out of 5 on average for accuracy. No one rated it below 2.

High ratings here are the norm, not a personal failing. If the tests came back negative yet your horoscope still nails you, this demo is the first clue. The full mechanism - why vague statements feel specific, how we fill in the gaps - is covered in why astrology still feels so accurate.

Who Believes in Astrology in the US: The Real Numbers

Pew Research Center surveyed 9,593 US adults in fall 2024 and published the results in May 2025. Twenty-seven percent of Americans believe in astrology, down slightly from 29 percent in 2017. Gallup found similar figures in the 1990s and 2000s - between 23 and 28 percent.

Thirty percent of US adults consult astrology, tarot cards, or fortune tellers at least once a year. Breaking that down: 28 percent consult astrology, 11 percent consult tarot, 6 percent consult fortune tellers, and 5 percent check astrology weekly.

Belief is highest among women aged 18 to 49 (43 percent) and adults aged 18 to 29 (33 percent).

The National Science Foundation's 2018 Science and Engineering Indicators found that about 58 percent of US adults consider astrology "not at all scientific," down from 65 percent in 2014. The NSF cautions that some survey respondents confuse astrology with astronomy, so treat that 58 percent carefully.

One viral claim you will see everywhere: "69 percent of Americans believe in astrology." That figure conflates reading horoscopes with believing them. The real belief number is 27 percent.

What 'Not Supported by Testing' Does - and Does Not - Mean

The record is clear: astrology has failed every controlled test to date. That phrasing is accurate. "Disproven" overstates what individual studies do and invites legitimate methodology objections (like the Ertel reanalysis). Science builds verdicts study by study, not by decree.

Not supported by testing does not mean worthless as a reflection prompt. I don't read daily horoscopes - I like the zodiac as a mirror, not a map. The chart can be a useful frame for thinking about yourself, the same way a personality quiz or a long conversation with a friend can be useful.

The tests checked whether the claims track reality. They do not. That does not make the symbolic framework useless for self-reflection, only unreliable as a predictive or diagnostic tool.

Never imply believers are unintelligent. Belief in astrology tracks stress and uncertainty, not intelligence. People reach for frameworks that offer meaning when life feels chaotic.

That is a human response, not a cognitive failure.

What each side cites - and what it actually shows

The claim Who cites it What it actually shows
Carlson's chance result Skeptics One rigorous double-blind test, not a universal disproof
Ertel's marginal p-values Astrological researchers A contested reanalysis, not a reversal of the peer-reviewed record
The null meta-analysis Skeptics The aggregate record - about 40 studies, no preference for correct charts
The Gauquelin Mars effect Astrological community A claimed effect from 1955 that failed independent replication
"69% of Americans believe" Viral posts Conflation of reading horoscopes with belief; real figure is 27% (Pew 2024)

Six things people get wrong about the science record

Myth: Astrology has been disproven.
Fact: "Failed every controlled test to date" is the accurate phrasing. Individual studies do not "disprove" - they test specific claims under specific conditions.

Myth: Most Americans believe in astrology.
Fact: Twenty-seven percent believe, per Pew's 2024 survey. The viral "69 percent" figure conflates reading horoscopes with believing them.

Myth: NASA data make astrology apps scientific.
Fact: Planetary positions are computable to high precision. That says nothing about whether interpretations of those positions track personality. The positions are real; the claimed correlations are what the tests checked, and the tests came back negative.

Myth: Scientists never bothered testing astrology.
Fact: The test record spans decades - double-blind matching, meta-analyses, large-N personality studies (see table above). The claim that science "never looked" is false.

Myth: The Ertel reanalysis overturned the Carlson study.
Fact: Ertel disputed the statistics and claimed marginal significance. Marginal p-values in a contested reanalysis are not a reversal. The mainstream reading stands.

Myth: If the tests failed, believers must be gullible.
Fact: Belief tracks stress and uncertainty, not intelligence. Reaching for meaning when life feels chaotic is a human response, not a cognitive failure.

FAQ: Astrology and Science, Straight Answers

What does 'for entertainment purposes only' actually mean?

It sets expectations - fun and reflection, not guidance - and echoes statutory carve-outs in some jurisdictions.

New York Penal Law section 165.35, for example, makes fortune telling for compensation a misdemeanor but exempts conduct "as part of a show or exhibition solely for the purpose of entertainment or amusement."

For a content site like this one, the line is honest framing with statutory roots, not a universal legal duty and not a trick.

Publishing and practicing belief is protected speech under the First Amendment.

Some states and cities regulate paid fortune-telling services through licensing requirements or old bans, and courts have struck several of those bans down (Argello v. City of Lincoln, 143 F.3d 1152, 8th Cir. 1998; Moore-King v. County of Chesterfield, 4th Cir. 2013; a 2012 Western District of Louisiana decision struck down Alexandria's ordinance).

This site sells no readings, so the question is moot here.

What percentage of Americans believe in astrology?

Twenty-seven percent of US adults, per Pew's 2024 survey of 9,593 people (down from 29 percent in 2017). The viral "69 percent" posts conflate reading horoscopes with believing them.

Separately, the National Science Foundation's 2018 data show about 58 percent of adults call astrology "not at all scientific," though the NSF cautions that some respondents confuse astrology with astronomy.

What is the Gauquelin Mars effect?

A claimed small statistical excess of Mars near the horizon in the birth charts of athletes, first reported by Michel Gauquelin in 1955. Independent replications failed to confirm it, and mainstream science does not accept it. It remains the single most-cited piece of positive evidence among astrologers who argue the test record is not entirely one-sided.

That is the honest summary believers deserve, even though the effect is not accepted science.

Do astrologers accept the scientific consensus?

The field is split. Psychological astrologers have largely dropped predictive claims and treat the natal chart as a symbolic reflection tool. Research-oriented astrologers still contest the test record and argue the studies missed what astrology actually does.

Either way, the major astrological organizations - AFA, NCGR, ISAR, OPA - all prohibit practitioners from giving medical, psychological, financial, or legal advice in their ethics codes.

If the tests failed, why does my horoscope still feel so accurate?

You just rated the same 1940s personality sketch that everyone else did, and most people rate it highly - 4.26 out of 5 on average in Forer's original experiment. Vague, flattering statements feel personal even when they apply to nearly everyone.

The full mechanism - the Barnum effect, confirmation bias, and how we fill in gaps - is covered in why astrology still feels so accurate.

The record is the record - what you do with it is yours.

If you keep a chart around, see how the big three actually get computed, or read why astrology still feels so accurate after everything above.

Sources

Dana Whitmore

is YouHoroscope's editorial voice: plain-spoken, curious, and allergic to mystification. No astrology credentials are claimed here - the published date tables do the proving.