If you’re one of the millions of people who turn to their horoscope to learn what the future might hold, then scientists have some bad news.
Proponents of astrology claim that the movement of the stars and planets can influence and even predict the behaviour and lives of humans on Earth.
If this were true, skilled astrologers should be able to predict the position of the stars at someone’s birth, or ‘birth chart’, just from information about that person.
However, an assessment of 152 astrologers found that their answers to this kind of test were no more accurate than guessing at random and almost always disagreed.
Despite almost a third of US adults believing in astrology, this study shows that there is absolutely no evidence to support one of the discipline’s few testable claims.
Astrologers claim to be able to predict someone’s life and personality based on the alignments of the planets at the moment of their birth. A new study has found they are no better at making these assessments than someone guessing at random (stock image)
Many modern astrologers claim that a person’s ‘birth chart’ – a tool recording the position of the heavenly bodies at a person’s time of birth – can be used to predict elements of their personality and life.
To try and expose astrology to a rigorous test, mathematician Spencer Greenberg joined forces with US social enterprise, Clearer Thinking.
In a post on X, formerly Twitter, Mr Greenberg explains: ‘One of the most fundamental claims of astrology is that a person’s natal chart contains information about that person’s life and character.
‘If true, astrologers should be able to correctly choose a person’s chart at a rate well above random guessing.’
Greenberg consulted with six astrologers to find out what kind of information they would need to know about someone’s life in order to work out their birth chart.
Researchers decided to test astrologers’ claims that birth charts (pictured) determine facts about a person’s life by asking them to match a description of a person to their corresponding birth chart
Using this information, the researchers created a questionnaire and selected 12 responses to be the basis of a test.
In the test, which you can try for yourself at this link, participants are given information about an unknown individual and asked which of five possible birth charts belongs to that person.
Mr Greenberg told New Scientist: ‘We asked, can we design a study where if astrology works, it’s very likely to come out in favour of astrology, and if it really doesn’t work, it’s likely that it’s going to come out against astrology.’
As an added incentive, anyone who managed to correctly answer 11 of the 12 questions would receive a $1,000 (£770) cash prize.
If astrology really did work then skilled astrologers should be able to match a person to their birth chart at a rate that is higher than chance. In this case that would mean being right more than 20 per cent of the time (stock picture)
In the test (pictured) astrologers failed to answer the questions with a better than random accuracy and almost always disagreed with each other
Of the 152 astrologers who completed the test, more than half were confident that they had got six more answers right.
However, on average the astrologers only got 2.49 out of a possible 12 answers correct – exactly what you would expect if they were guessing at random.
If astrology is not real you would expect to see a distribution of results with most getting about 20 per cent of the answers correct, a few getting more, and a few getting less.
When you compare the distribution of results expected by random guessers to those of astrologers you can see that they are an almost perfect match.
Mr Greenberg says: ‘It’s indistinguishable from random chance.’
Overall, not a single astrologer was able to answer more than five questions correctly, despite the majority believing they would be better than chance.
The distribution of right test results from astrologers (blue) almost exactly matches what you would expect if they were guessing at random (green) suggesting that astrology is not real
Nor was it just the case that less skilled or less experienced astrologers were dragging down the pack.
As part of the test, astrologers were asked to rate their experience from ‘I have a little experience’ to ‘I’m a world-class expert’.
But while the more experienced astrologers predicted they would be right more often, there was no statistically significant difference between the groups.
In fact, on average, those who ranked themselves as world-class experts performed marginally worse than those who said they had little experience.
Critically, the astrologers who took the test also had a very low level of agreement.
If astrology really is picking up on some details of the universe in a scientific manner, you would expect astrologers to give consistent answers to these kinds of tests.
Astrologers ranging from those with very little experience to world-class experts were equally unsuccessful
The only difference between the more and less experienced astrologers is that the more experienced participants were more confident in their abilities both before (blue) and after (orange) the test
However, the 152 astrologers who took the test rarely agreed on anything and even the most experienced group only gave the same answers 28 per cent of the time.
If all of the participants had been guessing at random, you would have expected them to agree 20 per cent of the time.
Mr Greenberg says: ‘This, to me, was really surprising. It suggests that astrology is maybe less standardised than you might think.’
To many, it might seem that astrology is a harmless enough distraction and hardly worthy of such intensive study.
But Mr Greenberg argues that this topic is just as worthy of study as any other.
On X, Mr Greenberg writes: ‘If astrology works, then that calls for a revolution in our scientific understanding of how the universe operates since modern physics provides no mechanism that could explain astrology.
‘On the other hand, if astrology doesn’t work at all, I also think that is very important because astrology is extremely widely believed.
In 2022, the mystical services industry which includes astrology, tarot cards, and palm reading was estimated to be worth $2.2 billion (£1.69bn) globally.
Mr Greenberg concludes: ‘Literally millions of people use it to guide their understanding of their lives, character, and future.
‘If it doesn’t work, they’d be better off seeking other sources of understanding and insight.’