MUL.APIN, the Babylonian star compendium

The tablet

A palm-sized clay tablet, written in cuneiform, holds the first part of a Babylonian star compendium.

The British Museum's tablet (opens in a new tab), museum number 86378, is a clay tablet about 86 by 60 millimetres, inscribed in two columns in the Akkadian language and cuneiform script. The museum describes it as an astronomical treatise, tablet 1 of the series MUL.APIN, “the plough star”, and as nearly complete.

It is catalogued as Late Babylonian (opens in a new tab), with a production date of 1000–500 BC, from southern Iraq. The standard edition the museum cites is Hermann Hunger and David Pingree's MUL.APIN, an astronomical compendium in cuneiform (1989).

Sources for this section British Museum, tablet 86378 (1899,0610.108): MUL.APIN, tablet 1 (opens in a new tab)

What it records

Three divisions of the sky, when the main stars rise, which rise and set together, and the stars on the Moon's path.

According to the museum's description (opens in a new tab), the tablet includes a list of the three divisions of the heavens; the dates on which the principal stars rise, in an ideal year of 360 days; the stars that rise and set together; and the constellations that lie in the path of the Moon.

That is careful, practical organisation of the sky: knowing which star rises when gave a way to keep track of the year. The IAU (opens in a new tab) notes that many cultures developed astronomy in just this way, to fix their calendars and foresee the seasons.

Keep in mind The tablet is a record of how stars were grouped and timed. It does not give a meaning or an omen for each of the 88 constellations used today; a later Babylonian tablet shows how some of its figures relate to the modern zodiac.

Sources for this section British Museum, tablet 86378 (1899,0610.108): MUL.APIN, tablet 1 (opens in a new tab) · ; International Astronomical Union, The Constellations (opens in a new tab)

What came after

Babylonian sky knowledge passed to the Greeks and beyond.

The British Museum's curators note, in their comments on a related tablet (opens in a new tab), that the sundial and the twelve divisions of the day reached Greece from Babylonia, and that Babylonian knowledge survived the end of cuneiform writing by translation into Aramaic and Greek, then Arabic and Sanskrit.

Some figures last to this day. Ian Ridpath (opens in a new tab) traces the scorpion of Scorpius to the Sumerian GIR-TAB, and the archer of Sagittarius (opens in a new tab) to the Babylonian god Pabilsag.

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: Scorpius (opens in a new tab) · ; Ian Ridpath, Star Tales: Sagittarius (opens in a new tab)

In the sky today

The stars it lists are the same stars you can see; the way they are grouped is Babylonian.

The Babylonian figures were groupings of their own, not the IAU's 88 areas. The IAU (opens in a new tab) explains that its constellations were fixed only in 1922 and 1928, drawing on the Greek patterns Ptolemy recorded.

Constellations, figures and asterisms explains how the modern system works, and the British Museum's zodiac tablet (opens in a new tab) shows Babylonian names beside modern ones.

Sources for this section International Astronomical Union, The Constellations (opens in a new tab) · ; British Museum, tablet 77824 (1885,0430.15): months and signs of the zodiac (opens in a new tab)