Babylonian astronomy

Babylonian astronomy collated earlier observations and divinations into sets of Babylonian star catalogues, during and after the Kassite rule over Babylonia. These star catalogues, written in cuneiform script, contained lists of constellations, individual stars, and planets. The constellations were probably collected from various other sources.

A connection to the star symbology of Kassite kudurru border stones has also been claimed, but whether such kudurrus really represented constellations and astronomical information aside from the use of the symbols remains unclear.

The first known formal catalogue of star lists are the Three Stars Each texts appearing from about 1200 BC. It mentions stars of Akkad, of Amurru, of Elam and others. Various sources have theorized a Sumerian origin for these Babylonian constellations, but an Elamite origin has also been proposed.

It includes a tripartite division of the heavens: the northern hemisphere belonged to Enlil, the equator belonged to Anu, and the southern hemisphere belonged to Enki. The boundaries were at 17 degrees North and South, so that the Sun spent exactly three consecutive months in each third.

The enumeration of stars in the Three Stars Each catalogues includes 36 stars, three for each month. The determiner glyph for “constellation” or “star” in these lists is MUL (𒀯), originally a pictograph of three stars, as it were a triplet of AN signs; e. g. the Pleiades are referred to as a “star cluster” or “star of stars” in the lists, written as MUL.MUL, or MULMUL (𒀯𒀯).

The second formal compendium of stars in Babylonian astronomy is the MUL.APIN, a pair of Babylonian tablets containing canonical star lists that were compiled around 1000 BC. The list is a direct descendent of the Three Stars Each list, reworked around 1000 BC on the basis of more accurate observations. They include more constellations, including most circumpolar ones, and more of the zodiacal ones.

Among the most ancient constellations are those that marked the four cardinal points of the year in the Middle Bronze Age, i.e. Taurus “The Bull”, from MULGU4.AN.NA (“The Steer of Heaven”), marking vernal equinox, Leo (“The Lion”), from MULUR.GU.LA (“The Lion”), marking summer solstice, Scorpius (“The Scorpion”), from MULGIR.TAB (“The Scorpion”), marking autumn equinox, and Capricornus (“Goat-Horned”), from MULSUḪUR.MAŠ (“The Goat-Fish”), marking winter solstice.

The path of the Moon as given in MUL.APIN consists of 17 or 18 stations. It lists, among others, 17 or 18 constellations in the zodiac, recognizable as the direct predecessors of the 12 sign zodiac. Later catalogues reduce the zodiacal set of constellations to 12, which were borrowed by the Egyptians and the Greeks, still surviving among the modern constellations.

The Babylonian star catalogues entered Greek astronomy in the 4th century BC, via Eudoxus of Cnidus and others. A few of the constellation names in use in modern astronomy can be traced to Babylonian sources via Greek astronomy.


Triangulum is a small constellation in the northern sky. Its name is Latin for “triangle”, derived from its three brightest stars, which form a long and narrow triangle. The white stars Beta and Gamma Trianguli form the base of the triangle and the yellow-white Alpha Trianguli the apex.

It is notable as the first constellation presented on (and giving its name to) the MUL.APIN (𒀯𒀳; “the Plough”), which is the current Triangulum plus Gamma Andromedae, corresponding to the first constellation of the year.

The Plough was the first constellation of the “Way of Enlil” – that is, the northernmost quarter of the Sun’s path, which corresponds to the 45 days on either side of summer solstice. Its first appearance in the pre-dawn sky (heliacal rising) in February marked the time to begin spring ploughing in Mesopotamia.


The path of the Moon as given in MUL.APIN consists of 17 or 18 stations, recognizable as the direct predecessors of the 12 sign zodiac. At the beginning of the list with MUL.MUL, the Pleiades, corresponds to the situation in the Early to Middle Bronze Age when the Sun at vernal equinox was close to the Pleiades in Taurus (closest in the 23rd century BCE), and not yet in Aries.

Taurus (Latin for “the Bull”) is a large and prominent constellation in the northern hemisphere’s winter sky. It hosts two of the nearest open clusters to Earth, the Pleiades, also known as the Seven Sisters and Messier 45, and the Hyades, both of which are visible to the naked eye.

Taurus is today the second astrological sign in the present zodiac. It spans from 30° to 60° of the zodiac. The Sun transits in this sign from approximately April 21 until May 21 in western astrology. It is a Venus-ruled sign, just like Libra.

It is one of the oldest constellations, dating back to at least the Early Bronze Age when it marked the location of the Sun during the spring equinox. Its importance to the agricultural calendar influenced various bull figures in the mythologies of Ancient Sumer, Akkad, Assyria, Babylon, Egypt, Greece, and Rome.

Taurus was the first sign of the zodiac established among the ancient Mesopotamians, who called it as “The Great Bull of Heaven”, because it was the constellation through which the Sun rose on the vernal equinox at that time.

Taurus marked the point of vernal (spring) equinox in the Chalcolithic and the Early Bronze Age, from about 4000 BC to 1700 BC, after which it moved into the neighboring constellation Aries. Cults centered around sacred bulls began to form in Assyria, Egypt, and Crete during The Age of Taurus, or “The Age of Earth, Agriculture, and the Bull”.

The name of the Pleiades comes from Ancient Greek. It probably derives from plein (“to sail”) because of the cluster’s importance in delimiting the sailing season in the Mediterranean Sea: “the season of navigation began with their heliacal rising”.

However, in mythology the name was used for the Pleiades, seven divine sisters, the name supposedly deriving from that of their mother Pleione and effectively meaning “daughters of Pleione”. In reality, the name of the star cluster almost certainly came first, and Pleione was invented to explain it.

The Hyades were in Greek mythology the five daughters of Atlas and half-sisters to the Pleiades. After the death of their brother, Hyas, the weeping sisters were transformed into a cluster of stars that was afterwards associated with rain.

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