Is astrology a science?
No — and the reason is specific enough to be worth understanding properly.
4 min read · Published 16 August 2026
The short answer
No. Astrology uses real astronomical data, but that does not make it a science, because the interpretive claims it makes are not structured to be testable. Karl Popper used astrology as his primary example when developing the criterion of falsifiability: a scientific claim must specify what observation would prove it wrong, and astrological claims almost never do. Where they have been made specific enough to test — most notably Shawn Carlson's 1985 double-blind study in Nature — they have not performed better than chance.
The distinction that actually matters
Astrology contains genuine science and is not one. Both halves are true and people usually drop one.
The astronomy is real. Planetary positions in a modern chart come from numerical models good enough to navigate spacecraft. There is nothing pseudoscientific about calculating where Mars was on your birthday; that is just arithmetic applied to an ephemeris.
The interpretation is where the claim to science fails. 'Mars was at 14° Leo' is a measurement. 'Which means you assert yourself dramatically' is a claim of an entirely different type, and it is that second step that has never been supported.
Popper and falsifiability
Karl Popper's problem was demarcation: what separates science from everything else that sounds like it? His answer was falsifiability. A scientific theory must forbid something. It must be possible to state in advance an observation that, if it occurred, would show the theory false.
Astrology was one of his central examples, alongside Freudian psychoanalysis and Marxist historical theory. His objection was not that astrologers were stupid or dishonest. It was that their theories could absorb any outcome. Whatever happened, an explanation was available afterwards — and a theory compatible with every possible result tells you nothing about which result to expect.
This is the sharpest thing that can be said against astrology, and it is sharper than 'the stars are too far away'. A theory does not have to have a known mechanism to be scientific. It has to be capable of being wrong.
What happened when it was tested
Shawn Carlson's study, published in Nature in 1985, is the most-cited attempt. Astrologers, working with birth charts, were asked to match each to one of three personality profiles. The design was double-blind and agreed with participating astrologers in advance. They performed at chance.
Other work has looked for correlations between birth data and occupation, personality measures and life outcomes. The pattern is consistent: where claims are specific enough to check, effects do not appear.
The best-known apparent exception is the 'Mars effect' — Michel Gauquelin's finding of an association between Mars placement and eminent athletes. It generated decades of dispute over sampling and replication and is not accepted as established.
What 'not a science' does not mean
It does not mean astrology is worthless, and this is where both sides usually overreach.
Literature is not a science. Neither is history's interpretive side, nor most of philosophy, nor any framework people use to think about their own lives. 'Not science' places astrology in an enormous category that contains a great deal of genuine value. What it does mean is that astrology cannot borrow science's authority — it cannot claim to have shown anything.
So the fair position is narrow. Astrology as a symbolic vocabulary for reflection: available, harmless, sometimes useful. Astrology as a source of factual claims about your future, your health or another person: not supported, and marketed that way constantly.
Where that leaves a chart
It leaves the computed parts intact and the interpretive parts labelled. That is exactly how AsterNym is built: positions from real ephemeris data, the zodiac and house system stated, uncertainty flagged when a birth time is missing, and a published list of things we refuse to tell you.
If you want the fuller version of the accuracy question rather than the demarcation question, that is how accurate is Western astrology.
Common questions
- Why is astrology considered a pseudoscience?
- Because its interpretive claims are not falsifiable — they do not specify in advance what observation would prove them wrong, so any outcome can be explained afterwards. Karl Popper used astrology as his central example when formulating this criterion.
- Has astrology ever been tested scientifically?
- Yes. The best-known test is Shawn Carlson's double-blind study published in Nature in 1985, in which astrologers attempted to match birth charts to personality profiles and performed at chance. Other studies looking for correlations with occupation and personality have found no reliable effects.
- Is the astronomy in a birth chart accurate?
- Yes. Planetary positions are computed from the same numerical models used for spacecraft navigation and are accurate to a fraction of a degree. It is the step from position to meaning that has no scientific support.
- What was the Mars effect?
- Michel Gauquelin reported a statistical association between the position of Mars and eminent athletes. It prompted decades of dispute over sampling methods and replication attempts and is not accepted as an established finding.