Mars Effect

The Mars effect is a purported statistical correlation between athletic eminence and the position of the planet Mars relative to the horizon at time and place of birth. This controversial finding was first reported by the French psychologist and "neo-astrologer" Michel Gauquelin published in his book L'influence des astres ("The Influence of the Stars", 1955) the first major study of astrology. Gauquelin suggested that a statistically significant number of sports champions were born just after the planet Mars rises or culminates. Gauqelin divided the plane of the ecliptic into twelve sectors, identifying two "key" sectors of statistical significance.

Gauquelin's work was accepted by the notable psychologist and statistician Hans Eysenck among others but later attempts to validate the data and replicate the effect have produced uneven results, chiefly owing to disagreements over the selection and analysis of the data set. Since the phenomenon in question depends upon the daily rotation of the Earth, the availability and accuracy of time and place of birth data is crucial to such studies, as is the criterion of "eminence". Later research explains the Mars effect by selection bias, favouring champions who were born in a key sector of Mars and rejecting those who were not from the sample.