The predictions catalog for 2025, which I obtained from a popular astrology app for $11.25, forecasts that next winter I will lose myself in love and be swept away by the ecstatic feeling of being part of something bigger than myself. Notice that this may refer to a romantic entanglement, a new job, or joining an NGO, a political party, a cult, Christmas carolers, or a barn dance group — among an infinite number of other possibilities. Perhaps the publication of my book will attract an enthusiastic fan base that will shower me with love and adulation. Who knows? The language is bold, but when you put it all together, any pretense at substance vanishes.

Rhetorical techniques and even some psychological biases combine to make astrological pronouncements sound more impressive than they deserve. But even expert astrologers sometimes slip and make predictions that can be objectively evaluated, with results that are not so good.

At the beginning of 1914, the magazine Modern Astrology, brainchild of Alan Leo, confidently predicted a year of peace for Europe. World War I would break out in August. In 1956, the German astrologer Carl Heinrich Huter, publisher of a popular series of astrological almanacs, predicted that Queen Elizabeth II would have a short reign: “Anyone looking at the horoscope of Queen Elizabeth II will be deeply stirred by the ominous position of Saturn … all rulers and politicians with Saturn in this position have either been overthrown or have abdicated of their own free will. There is not a single known exception in the whole of world history.” Of course, Elizabeth II reigned from 1952 until her death in 2022, the longest reign in British history and the longest by any queen anywhere. (Huter, by the way, has been identified as the originator of a fabricated quote, falsely attributed to Albert Einstein, endorsing astrology.)

Astrological predictions can also always be revised after the fact. When the marriage of Prince (now King) Charles and Diana Spencer was first announced, British astrologers were quick to say that their birth charts were highly compatible; after their painful separation in 1992, exactly the same charts suddenly showed “only trauma, anger, rebellion, and disaster.” The same astrologer who wisely predicted, but only after the fact, that the royal marriage would be a dismal one also predicted that Diana would have a “lively” existence and be “revolutionary” in the 21st century. She, of course, died in a car accident in 1997. Prince Henry, today famous for having married an American actress, Meghan Markle, leaving the royal family behind, and writing a scandalous autobiography, was astrologically characterized as a “conservative” who would be attracted to “old-fashioned” women and who would probably, given the chance, be a better king than his older brother, William.

Astrologers always do much better work on finding stars and planets to explain the past than on using them to foresee the future. In October 1914, after the war had begun, Alan Leo finally found an astrological configuration for that year signifying conflict and “the downfall of monarchs.”

Observational tests of wrong charts happen when astrologers are called to build birth charts of people whose lives and personalities are known but, for some reason, receive incorrect data. In real science, when experts receive data that are incompatible with what they were told to expect — say, an astronomer who receives orbital data from Venus but under the mistaken label “Mars”— the discrepancy is quickly noted. This also should be true for astrologers if their system had any basis. 

The famed British occultist Aleister Crowley, who ghost-wrote a pair of astrology handbooks for America’s first pop-star astrologer, Evangeline Adams, bragged in a letter that astrology allowed him to correctly guess the time of birth of his friends almost to the minute, even sometimes correcting them. There’s no evidence to support Crowley’s braggadocio — he is always an unreliable narrator at best — but there’s a long list of instances in which eminent astrologers, fed misleading data about leaders and celebrities, managed to fail to find anything wrong and went on to create chart interpretations that were “just so” for the known biographies and personalities.

The Italian mathematician and astrologer Gerolamo Cardano, one of the most influential astrologers of the Renaissance, once published a birth chart of Emperor Nero of Rome that perfectly explained all the character flaws of that tyrant in terms of the planets — Mars, Venus, and Saturn were particularly implicated—and even his violent death. Soon after, however, Cardano discovered that the birthdate he’d used was wrong by two and a half years. “He silently expunged his earlier analysis and substituted a totally new figure for the old one.”

Another blooper by Cardano — and one he couldn’t hide — involved British royalty. His horoscope for young King Edward VI, delineated when the boy was 15, predicted a somewhat happy and fruitful adult life, even if not necessarily a healthy one, including a good marriage. But the king died, still single and still a teenager, some months before the publication of the book containing the analysis. Cardano’s excuse was that he had deliberately circumvented any calculations that might imply risk to avoid any political awkwardness. He bragged that if he had made the missing calculations, he’d have seen the danger.

The book Understanding Astrology: A Critical Review of a Thousand Empirical Studies 1900–2020 (2022) tells that at least six different birth charts of the British statesman Winston Churchill were published before Churchill’s correct birth time became known. All tried to “reverse engineer” the correct time (necessary for the proper calculation of ascendant, houses, etc.) from Churchill’s public life, personality, and the outstanding points of his career; all gave very compelling interpretations, perfectly fitting stars to man. All were wrong.

The astrologer Albert George Samuel Norris went as far as publishing an astrological biography of Churchill in 1957, calculating the missing elements from the known facts of Churchill’s life. The book has more than 300 pages, including two chapters on the “scientific basis” for his extrapolations. He wrote that if his calculations of the time of birth — based, among other things, on the position of Pluto during the politician’s knighting in 1954 — were wrong, it would be a “blow” to astrology. Norris was, in fact, four hours off the mark. 

In 1971, the British astrologer Klara Henderson published a detailed study of the birth chart of the Soviet leader Vladimir Lenin. The reading fit the man perfectly, but the chart used was from 12 days before Lenin’s actual birthday, a discrepancy perhaps caused by the divergence between the Gregorian and Julian calendars, the latter of which was used in the Russian Empire until it was abolished by the Bolsheviks in 1918 and still employed when Lenin was born. By the 20th century, the Julian calendar had accumulated a 13-day delay relative to the Gregorian calendar, adopted in the West between the 16th and 18th centuries. The chart used by Henderson contained several important mistakes, including the sun sign (Lenin was a Taurus; Henderson had him as an Aries) and the positions of various planets. Nonetheless, she produced a very compelling analysis.

To date, Understanding Astrology is the most comprehensive critical review of attempts to evaluate the validity of astrology, doing so over more than 900 pages. [It’s authors, Geoffry Dean, Arthur Mather, David Nias, and Rudolf Smit, go] into the statistical minutiae necessary to separate spurious effects from real ones. Their conclusion: “The case for astrology is that it can provide meaning for human existence, at least for those people who find it hard to understand the world rationally. The case against astrology is that it is factually untrue and thus potentially harmful.”