Sceptical Astrology: What Does the Research Say?

• A. The Moon's phases directly cause changes in human mood and behaviour.
• B. The positions of celestial bodies at the time of a person's birth are related to their personality and life events. ✓
• C. Planets exert gravitational forces strong enough to influence the outcome of individual decisions.
• D. Stars emit unique radiation that is absorbed by the human nervous system at birth.

Why: Astrology holds that the positions of the Sun, Moon, and planets at the moment of a person's birth, often mapped in a birth chart, correlate with character traits and future events. The other options describe physical mechanisms (lunar phase effects, gravity, stellar radiation) that astrologers do not typically rely on for their core claims, and that are either scientifically unsupported or negligible at the scale of a human being.

• A. A scientific catalogue of all known stars in the Milky Way.
• B. A belt of twelve constellations along the ecliptic, each associated with a sign used to interpret planetary positions. ✓
• C. A table of planetary orbital periods used by NASA for spacecraft navigation.
• D. A list of ancient Greek gods associated with each month of the year.

Why: The zodiac is a band of sky centred on the ecliptic, the apparent path of the Sun through the year. Astrology divides it into twelve signs of 30 degrees each, which are used as symbolic categories. Note that these signs are not the same as the modern constellations of the same names, a discrepancy largely caused by the precession of the equinoxes.

• A. A sun sign uses only the Sun's position, while a birth chart uses the positions of multiple planets, the Ascendant, and house divisions at the exact time and place of birth. ✓
• B. A sun sign is calculated from the date of death, while a birth chart is calculated from the date of birth.
• C. A sun sign is a measure of solar brightness, while a birth chart measures the temperature of the planets.
• D. There is no difference; the terms are interchangeable in all astrological traditions.

Why: The sun sign is determined solely by which zodiac sign the Sun occupied on a person's birth date, which is why it is so widely known. A birth chart is far more detailed, requiring the precise birth time and location to place the planets, the rising sign (Ascendant), and the twelve houses. Sceptics note that the precision required for birth charts makes them sensitive to small errors in recorded birth times.

• A. Astrologers have never made any predictions at all.
• B. Astrology cannot mechanistically explain how distant planets would influence individual personalities, since the gravitational and electromagnetic effects of the planets on a newborn are negligible compared with those of the obstetrician and the hospital environment. ✓
• C. Astrology is based on modern particle physics that has been disproven.
• D. Astrology has been endorsed by every major scientific academy in the world.

Why: A central sceptical argument is the lack of a plausible physical mechanism: the gravitational pull of the doctor or a nearby building on a newborn exceeds that of distant planets, and no known force carries planetary positions to the infant. Option A is false, since astrologers make many predictions. Option C misstates the situation, as astrology predates modern physics and is not based on it. Option D is false; major scientific bodies have found no support for astrology.

• A. Anecdotal case reports collected from astrologers' clients.
• B. Double-blind tests in which participants match birth charts to personality profiles without knowing which profile belongs to their own chart. ✓
• C. Surveys asking people whether they believe their horoscope fits them.
• D. Historical reviews of famous people's birth dates.

Why: Blind matching studies, such as the well-known 1985 Shawn Carlson study published in Nature, present participants with birth charts and personality profiles and ask them to match the two without knowing the correct pairings. This controls for the Barnum effect and confirmation bias. Such studies have generally found performance no better than chance. Anecdotes and self-reported belief are vulnerable to bias and cannot establish causation or accuracy.

• A. Ancient Egypt
• B. Mesopotamia (Babylonia) ✓
• C. Ancient Greece
• D. The Maya

Why: Mesopotamian scholars, particularly in Babylonia, recorded celestial observations systematically from around the second millennium BCE and developed omen-based astral divination. Greek astrology later drew heavily on these Babylonian traditions.

• A. To predict individual personality traits at birth
• B. To interpret celestial events as signs relevant to the king and the state ✓
• C. To calculate the exact position of planets for navigation
• D. To determine the most auspicious dates for agricultural planting

Why: Much Babylonian astral divination was state-oriented, with celestial phenomena such as eclipses and planetary movements read as messages concerning the king, the realm, or political events. Individual horoscopic astrology developed later, in the Hellenistic period.

• A. The Almagest by Ptolemy
• B. The Tetrabiblos by Ptolemy ✓
• C. The Elements by Euclid
• D. The Natural History by Pliny the Elder

Why: Claudius Ptolemy's Tetrabiblos systematized astrological theory, covering planetary influences, signs, and houses. His Almagest, by contrast, is an astronomy treatise, which is why the two are often confused.

• A. Astrologers and astronomers were the same professionals, and their methods, records, and institutions were often shared ✓
• B. Astronomy adopted astrological methods to improve its predictions
• C. Governments required both disciplines to be taught in the same universities
• D. Astrology preceded all observational astronomy by several thousand years

Why: In antiquity and the medieval period, the same scholars often practiced both astronomy and astrology, and the mathematical techniques for calculating planetary positions served both purposes. This shared heritage explains why the two were not clearly separated until the early modern period.

• A. The discovery of the planet Neptune
• B. Kepler's and Galileo's work, along with the broader development of the scientific method and mechanistic physics ✓
• C. The publication of the first printed star charts
• D. Papal condemnation of all forms of divination in 1600

Why: Discoveries by Kepler and Galileo, together with Newtonian mechanics and the growing emphasis on empirical testing, moved astronomy toward a physics of causes that had no place for astrological influence. Astrology was increasingly seen as lacking a plausible physical mechanism, which led to the separation of the two fields.

• A. Significantly better than chance, supporting astrology
• B. At roughly chance level, with no reliable match between charts and profiles ✓
• C. Worse than chance, showing astrologers systematically chose the wrong charts
• D. Only accurate when the astrologers were told the subjects' birth dates

Why: Carlson's study, published in Nature, found that astrologers could not match natal charts to the correct personality profiles above chance level under double-blind conditions, which undermined claims that charts reflect personality.

• A. It proves that astrologers are deliberately deceptive
• B. People tend to rate vague, general personality descriptions as highly accurate for themselves ✓
• C. It shows that birth charts contain hidden personal information
• D. It explains why astrologers always make correct predictions about the future

Why: The Barnum (or Forer) effect describes how people accept broad, flattering, or vague statements as uniquely true of themselves, so a high self-rated accuracy does not show that a reading was specific or predictive.

• A. Asking only the person who believes in astrology to judge the accuracy
• B. Choosing predictions after seeing the outcomes so they seem correct
• C. Making predictions in advance and checking them against outcomes without knowing which reading belongs to which person ✓
• D. Using only horoscopes from newspapers that are written to be vague

Why: Recording predictions beforehand and evaluating them blind prevents hindsight bias and expectation effects, which are major sources of false confirmation in astrology tests.

• A. Strong, replicated support for astrological compatibility
• B. Apparent planetary-position effects that largely failed to replicate under independent, rigorous testing ✓
• C. No data was ever collected on the subject
• D. Results that were fully confirmed by the astrology community's own studies

Why: Gauquelin reported small statistical associations (such as the 'Mars effect'), but attempts by independent researchers, including the Committee for the Scientific Investigation of Claims of the Paranormal, failed to reproduce them under controlled conditions.

• A. Planets are too far away to have any gravitational effect at all
• B. The gravitational and other physical forces exerted by the nearby obstetrician and hospital equipment at birth are far larger than those of distant planets ✓
• C. Planets only influence the weather, not human beings
• D. Astrology uses the wrong calendar, so the charts are misaligned

Why: Gravitational pull from ordinary nearby objects, such as the doctor or delivery room equipment, far exceeds the tiny gravitational effects of distant planets, so proposed physical mechanisms for astrological influence are considered implausible.

• A. A tendency to rate vague, general personality descriptions as highly accurate for oneself
• B. A tendency to rate vague, general personality descriptions as highly accurate for oneself ✓
• C. The finding that people with birthdays in the same month share personality traits
• D. A statistical method for detecting planetary influences on human behaviour

Why: The Barnum effect (also called the Forer effect) describes how people tend to accept broad, flattering, and vague personality descriptions as uniquely accurate for themselves, even when the same description is given to everyone.

• A. In a laboratory study of memory recall using astrological charts
• B. In a classroom where students were given identical personality profiles built from a generic text and asked to rate their accuracy ✓
• C. In a survey of professional astrologers about their client outcomes
• D. In a clinical trial of antidepressant medication

Why: Forer gave his students a personality sketch that was essentially the same for everyone, drawn from a horoscope-style text. Most students rated it as highly accurate, showing that generic statements can seem personally tailored.

• A. They are based on precise measurements of planetary positions at birth
• B. They include specific, verifiable predictions about dates and events
• C. They use broad statements that could apply to nearly anyone, such as 'you have a great need for other people to like you' ✓
• D. They are written by trained psychologists using validated scales

Why: Statements that are vague, flattering, and applicable to almost everyone are easy to match with one's own experience. Their generality, not any astrological insight, drives the sense of accuracy.

• A. Astrologers deliberately withhold their best insights from researchers
• B. Planetary influences are too weak to affect human personality at all
• C. Participants can recognise their own chart only when they already know which chart is theirs, so the Barnum effect inflates their ratings when the match is open and fails when it is blind ✓
• D. Birth time records are usually inaccurate, so charts cannot be cast correctly

Why: In blind matching tests, people must pick the chart that fits them without knowing which is theirs. Performance falls to chance, which shows that the apparent accuracy of individual readings comes from how the descriptions are presented rather than from any real correspondence.

• A. Trust descriptions that feel especially personal and specific to you
• B. Check whether the description also fits people with very different birth dates and whether it contains concrete, falsifiable claims ✓
• C. Rely on how strongly the description matches your self-image
• D. Assume accuracy whenever the description is consistent with astrological tradition

Why: A description that fits people born at any time of year, and that avoids testable claims, cannot distinguish accurate from inaccurate readings. Checking across groups and looking for falsifiable content are standard ways to separate real insight from the Barnum effect.

• A. That people born when Mars is rising or culminating are overrepresented among sports champions ✓
• B. That people born under the Sun sign of Aries are more likely to be born in spring
• C. That astrological houses correlate with the number of children a person has
• D. That birth rates peak during full moons across all countries

Why: Gauquelin reported that sports champions were more often born with Mars in certain positions. Later attempts at replication, including a large-scale test by the Committee for Skeptical Inquiry, failed to confirm the effect once the data were properly controlled, suggesting the original result was due to chance or methodological issues.

• A. Roughly 1 in 1000
• B. Roughly 1 in 10
• C. Roughly 1 in 2 ✓
• D. Exactly 0

Why: Long runs appear surprisingly often in random sequences. Over 10 flips, a run of 5 or more same-faced outcomes occurs in roughly half of all sequences, illustrating how humans tend to underestimate how common apparent patterns are in pure chance.

• A. It shows that horoscope writers are deliberately trained to use scientific language
• B. It describes people's tendency to rate vague, general personality descriptions as highly accurate for themselves ✓
• C. It proves that star charts become more accurate with each passing year
• D. It explains why birth certificates are often recorded incorrectly

Why: In Forer's 1949 study, students rated a generic personality profile, which was identical for everyone, as highly accurate. Astrology readings often rely on such broad statements, so people may feel they fit even when the descriptions are not specific to them.

• A. A group of astrologers who make predictions without seeing any birth data
• B. A group whose members are not given any astrological information, so results can be compared against those who are ✓
• C. A group born on the same day as the researcher
• D. A group of people who have already been told their horoscope

Why: A control group provides a baseline for comparison. To show astrology works, researchers need to see whether people who receive a sign-based reading perform better than those who do not, ruling out expectation effects and chance.

• A. Horoscopes are never written in the past tense
• B. The friend is only remembering the hits and not counting the many predictions that failed, which is confirmation bias ✓
• C. Astrology cannot make predictions about future events at all
• D. Horoscopes are always accurate for people born in winter

Why: Confirmation bias leads us to notice and remember matches while overlooking misses. Without recording all predictions and checking hit rates against a baseline, a few memorable successes cannot establish that the method works.

• A. The Dunning-Kruger effect
• B. Confirmation bias ✓
• C. The bystander effect
• D. Cognitive dissonance reduction through groupthink

Why: Confirmation bias is the tendency to notice, remember, and weight evidence that supports existing beliefs while discounting contrary evidence. When a horoscope matches a person's experience, the match is salient; the misses are easily forgotten.

• A. They were written in highly technical astrological language
• B. They were tailored to each participant's birth chart
• C. They were vague and general enough to apply to almost anyone ✓
• D. They contained predictions about future events

Why: In Bertram Forer's 1949 experiment, students were given the same generic personality profile, yet most rated it as highly accurate. Vague, flattering statements that apply to nearly everyone create the illusion of individual insight.

• A. Astrology has been scientifically proven to predict life events
• B. It offers a sense of meaning, structure, and perceived control over an unpredictable world ✓
• C. It requires expensive training that signals social status
• D. Astrologers are legally required to provide emotional counselling

Why: Research on belief in the paranormal and pseudoscience suggests that people under stress or uncertainty often seek explanatory frameworks that make events feel patterned and meaningful, which astrology readily provides.

• A. It confirmed that planetary positions determine personality
• B. It was a notable attempt to test astrological claims statistically, and the results were not replicated under independent scrutiny ✓
• C. It proved that astrologers can predict the future
• D. It showed that astrology is used exclusively by the uneducated

Why: Gauquelin reported that athletes were more often born when Mars was in certain positions. The claim generated debate, but attempts at independent replication, including by sceptics, failed to confirm the effect, and it is commonly discussed as a case of how statistical patterns can seem meaningful without a causal basis.

• A. Editors are required by law to publish them
• B. They are cheap, entertaining, and generate reader engagement, so media incentives favour keeping them ✓
• C. Scientists have never tested them
• D. They have been officially endorsed by major scientific bodies

Why: Horoscopes persist largely because of cultural tradition and commercial incentives: they are inexpensive content that attracts readers, and their entertainment value and habitual readership sustain them regardless of their empirical record.