A Babylonian zodiac, with older names

The tablet

A complete tablet of fired clay, about the size of a playing card, lists the months and their signs.

The British Museum's tablet 77824 (opens in a new tab) is fired clay, complete, 6.7 by 4.7 centimetres, inscribed in Late Babylonian script with a list of months and the signs of the zodiac associated with them. The museum dates it to about 500 BC and records its findspot, with question marks, as Sippar or Babylon.

The museum's curators call it an important stage (opens in a new tab) in the development of the zodiac as we know it, and write that the twelve-part zodiac derives from ancient Mesopotamian ideas and images, some already present among divine symbols in the second millennium BC, developing gradually until by the end of the first millennium BC it underpinned both astrology and astronomy.

Sources for this section British Museum, tablet 77824 (1885,0430.15): months and signs of the zodiac (opens in a new tab)

Twelve months, fifteen figures

Some months carry two figures: the Pleiades with the Bull of Heaven, Orion with the Great Twins.

The tablet gives two figures for three of the months (opens in a new tab): the Pleiades and Taurus for the second, Orion and Gemini for the third, Pegasus and Pisces for the twelfth.

The table below gives the museum's translations (opens in a new tab) of the Babylonian names, beside the modern equivalents the museum gives. The right-hand column is the museum's identification, not a word on the tablet.

Sources for this section British Museum, tablet 77824 (1885,0430.15): months and signs of the zodiac (opens in a new tab)

Reading the list carefully

Familiar animals sit beside unfamiliar ones: a hired man, a barley-stalk, a goat-fish, a field.

Several figures will look familiar: the Crab, the Lion, the Balance, the Scorpion. Others will not. Where the modern list has Aries, the tablet has a hired man (opens in a new tab); where it has Virgo, a barley-stalk; where it has Capricorn, a goat-fish, part goat and part fish; where it has Aquarius, a giant.

The archer of the ninth month is Pabilsag, a god. Ian Ridpath (opens in a new tab) describes the Sumerian figure PA.BIL.SAG as a winged centaur-archer, a god of war and hunting, which the Greeks took over without its wings.

Keep in mind The tablet equates months with sky figures, which the museum treats as a stage on the way to the twelve signs. It is not the twelve equal 30° signs of later astrology, and a modern horoscope wheel is not an unchanged copy of it; the zodiac and Ophiuchus explains the difference.

Sources for this section British Museum, tablet 77824 (1885,0430.15): months and signs of the zodiac (opens in a new tab) · ; Ian Ridpath, Star Tales: Sagittarius (opens in a new tab)

In the sky today

The stars are still there; the figures drawn on them have changed hands.

The Bull of Heaven is today's Taurus, and Ridpath (opens in a new tab) notes the Sumerian name GUD AN-NA for it, facing the hero in Orion.

The Balance was later absorbed into the Greek scorpion's claws and separated again: the Greeks (opens in a new tab) called the claws Chelae, and the Romans made them the constellation Libra in the first century BC.

Sources for this section Ian Ridpath, Star Tales: Orion (opens in a new tab) · ; Ian Ridpath, Star Tales: Scorpius (opens in a new tab)