Where astrology comes from: Babylon, Greece and after

Babylon: omens before horoscopes

Astrology was not born with horoscopes but with omens. In Mesopotamia, from the 2nd millennium BC, scholars noted what happened in the sky — eclipses, haloes, conjunctions, appearances of Venus — and what followed on earth: the death of a king, a flood, a defeat. The great series Enūma Anu Enlil, some seventy tablets known mainly from the copies in Ashurbanipal’s library at Nineveh (7th century), is their collection: “if the Moon is surrounded by a halo and Jupiter stands in it, the king will be besieged”. These omens concerned the state, not individuals, and the astronomer-scribes sent their reports to the palace like intelligence bulletins.

To predict rather than record, mathematics was needed. The compendium MUL.APIN, around 1000 BC, catalogued the stars and their periods; in the 5th century, Babylonian astronomers took a decisive step: they divided the band of sky in which the Sun, Moon and planets travel into twelve equal parts of 30 degrees, named after the neighbouring constellations. The zodiac was born — not as an observation, but as a calculating tool, a coordinate system. The first known individual horoscopes follow shortly after: the oldest, on a cuneiform tablet, concerns a child born in April 410 BC; about thirty have been found, soberly listing the positions of the heavenly bodies at birth, sometimes with a line of prognosis.

Alexandria: the invention of the birth chart

Astrology as we know it — the chart drawn for an individual, with ascendant, houses, aspects and rulerships — is a Hellenistic creation, born in Ptolemaic Egypt in the 2nd and 1st centuries BC, where the Babylonian zodiac met Greek astronomy and the Egyptian tradition of the decans, the 36 stars or star groups whose rising marked the hours of the night. The founding treatises, attributed to a legendary pharaoh and priest, Nechepso and Petosiris, are lost, but their heirs survive: the Latin poem of Manilius (1st century), the Carmen astrologicum of Dorotheus of Sidon, the Anthology of Vettius Valens (2nd century), full of real clients’ charts, and above all the Tetrabiblos of Claudius Ptolemy, around 150, which gives astrology its physical justification — the heavenly bodies act through heat, cold, moisture and dryness — and fixes it for fifteen centuries. The word itself comes from there: hōroskopos, “hour-watcher”, denoted the point of the ecliptic rising at birth, our ascendant.

One detail in Ptolemy would have immense consequences: he anchors the zodiac to the spring equinox and not to the stars. In his time the two almost coincided; precession has since pulled them 24 degrees apart, which is why Indian astrology, which stayed sidereal, does not give the same signs as ours. The zodiac carved on the ceiling of the temple of Dendera, around 50 BC and now in the Louvre, shows the moment when Greek signs and Egyptian decans merged.

Rome: banned and everywhere

In Rome astrology is at once practised at the top and regularly banned. Augustus has Capricorn, his sign, struck on his coins; Tiberius keeps the astrologer Thrasyllus at his side; and the Senate expels the “Chaldeans” from the city several times, from 139 BC onwards, because predicting an emperor’s death is a political crime. An edict of Augustus, in AD 11, forbids private consultations and questions about anyone’s death. The early Church then sees in it a denial of free will, and the Fathers condemn it — without stopping early medieval bishops from reading it.

India, Baghdad, Toledo: the long detour

The Greek chart travelled east from the 2nd century: the Yavanajataka, “the horoscopy of the Greeks”, adapted it into Sanskrit, and India grafted it onto its own nakshatras to produce jyotish, which remains today the most living astrological tradition in the world. It also travelled to Baghdad: the city itself was founded in 762 on a date chosen by the caliph’s astrologers, and Masha’allah, Abu Ma’shar (9th century) and al-Biruni translated, criticised and enriched the Greek and Persian heritage — solar returns, the “lots”, the great conjunctions of Jupiter and Saturn that were supposed to pace the history of empires and religions. It was through their books, translated into Latin at Toledo and elsewhere in the 12th century, that Europe rediscovered the Ptolemy it had forgotten.

In the Middle Ages and the Renaissance, astrology was a university discipline, taught alongside medicine: one bled according to the Moon’s sign, drew the “zodiac man” in books of hours, chose the hour of battles and princely weddings. The Church distinguished “natural” astrology, admitted, from “judicial” astrology claiming to read people’s destinies, condemned by the bulls of Sixtus V (1586) and Urban VIII (1631) — the latter himself a great consumer of horoscopes. Nostradamus published his Prophecies in 1555; Kepler drew charts for Wallenstein while writing that astrology was astronomy’s “foolish daughter”, who fed her mother; Galileo cast them for his daughters and his patrons, and the Inquisition of Padua investigated him in 1604 for astrological fatalism.

The break, then the return

What killed learned astrology was not a refutation but a change of world. With Copernicus, Kepler and Newton, the Earth ceased to be the centre towards which the heavenly bodies “radiate”, the planets became ordinary bodies subject to gravitation, and Ptolemy’s physical justification collapsed without being replaced. In one century, from 1650 to 1750, astrology disappeared from universities and courts; it survived in popular almanacs — England’s Old Moore’s Almanack has appeared without interruption since 1697 — and with a few practitioners such as William Lilly, whose Christian Astrology (1647) is the first great manual in a vernacular language.

The return came from England in the 19th century, carried by the almanacs of “Raphael” and “Zadkiel”, then by theosophy. Alan Leo (1860–1917), theosophist and publisher, did two decisive things: he moved astrology from prediction to the description of character — less vulnerable in court, where he was twice prosecuted for fortune-telling — and he simplified everything around the Sun sign, which can be known without a chart. The next step was a newspaper: on 24 August 1930 the Sunday Express published the horoscope of Princess Margaret, born three days earlier, written by R. H. Naylor; the success was such that the paper commissioned a column from him, and the press of the whole world followed. The newspaper horoscope, with its twelve paragraphs, dates from there: it is less than a century old.

The 20th century added a psychological layer — Jung took an interest and coined “synchronicity” to account for it without causality, Dane Rudhyar and Liz Greene made it a language of personality — and a layer of tests. Michel Gauquelin believed in 1955 that he had found a “Mars effect” among sports champions, which thirty years of controversy would attribute to selection biases; in 1985, Shawn Carlson’s double-blind test, published in Nature, showed that seasoned astrologers matched charts to personality profiles no better than chance; in 2003, the “time twins” study — more than two thousand Londoners born minutes apart in 1958 — found no particular resemblance between them. Astrology has lost none of its popularity for all that: about one adult in four, in Europe and North America, says they believe in it at least a little.

Why there are two zodiacs

The Earth’s axis of rotation slowly describes a cone, like a spinning top’s, in about 25,800 years. The point of the ecliptic where the Sun stands at the spring equinox therefore slips back among the stars by one degree every 72 years, a whole sign every 2,150 years: this is the precession of the equinoxes, known since Hipparchus in the 2nd century BC. The tropical zodiac of Western astrology follows the equinox — Aries always begins in spring — and its signs no longer coincide with the constellations whose names they bear: when the Sun is “in Aries” for an astrologer, it stands before the stars of Pisces for an astronomer. The sidereal zodiac of India follows the stars. The gap between the two, the ayanamsa, is 24 degrees in 2026. The famous “Age of Aquarius” is only the passage of the vernal point from Pisces into Aquarius — whose date, depending on where the boundary between the constellations is drawn, varies by several centuries.

And the other astrologies?

Chinese astrology has an independent origin: it rests on the calendar and the sixty-year cycle, not on the Greek planetary chart, even if exchanges along the Silk Road brought Indian and Iranian elements to China. The Maya tzolk’in is a divinatory calendar unconnected with the Old World. Indian astrology, on the other hand, is a true daughter of the Greek chart, which kept the zodiac of the stars and invented the division of life into planetary periods.

Frequently asked questions

Why twelve signs?

Because a year contains roughly twelve lunations, and because the Babylonians counted in base sixty: twelve parts of thirty degrees give a circle of 360, convenient for calculation. The real constellations are of very unequal size; the equal zodiac is an abstraction.

Is there a thirteenth sign?

No. The ecliptic does cross the constellation Ophiuchus, which went round the world in 2016 after a NASA blog post, but astrological signs are 30° divisions counted from the equinox, not constellations: they are twelve by construction, and Ophiuchus changes nothing. The question mixes astronomy and astrology.

Was astrology ever a science?

It was a learned discipline, taught at university and practised by great astronomers, as long as the model of the world gave it a plausible mechanism. It ceased to be one when that model changed, and modern tests have found no effect in its place. It remains a fascinating subject of history and a symbolic language — which is how this site treats it.

Since when have there been horoscopes in newspapers?

Since 1930 in Britain, and the following years elsewhere. Annual almanacs had existed for centuries, but the paragraph per sign, weekly then daily, is an invention of the 20th-century press.