Astronomy began with the first settlements of agricultural societies. Mesopotamia, the land between the Tigris and Euphrates rivers in what is today Iraq, was the birthplace of civilization almost 10,000 years ago. It is in ancient Sumeria that we find the oldest records of the study of astronomy. Babylon and Assyria were later civilizations in the same geographic area, and inherited the Sumerians' astronomical traditions and many of their myths and legends surrounding the skies. They in turn developed their own astronomical culture and passed it on to the Greeks and eventually to our modern world. Perhaps the greatest legacy to modern western astronomy was left to us by the Babylonians. We still use many of their original constellations, and the records they kept of astronomical occurences allow us a glimpse into their view of the heavens.

Purposes of Astronomy in Ancient Mesopotamian Civilization

As in most ancient cultures, astronomy was actually practiced as astrology. Astronomical events, whether they were every-day occurences or rare incidents, had a deep religious meaning for the people. It was believed that all things happened for a reason. This spiritual angle often spilled over onto the social or political levels as well. Kings and nobles relied heavily on omens which were witnessed and interpreted by a powerful group of priest-astronomers. Lives were lived according to the advice of these astronomers, who seemingly were able to understand the universe and make predications based on their observations.

A great deal of astronomical mythology was handed down from the Sumerians. Constellations that we still use today, such as Leo, Taurus, Scorpius, Auriga, Gemini, Capricorn, and Sagittarius, were invented by the Sumerians and Babylonians between 2000-3000 B.C. These constellations had mythical origins, the stories of which are common throughout the western world. The Babylonians created a zodiac, which marked the twelve constellations that the sun, moon, and planets travel between during their movements through the sky.

However, besides being the manifestation of legends, the constellations provided a practical use for the people of ancient Mesopotamia. Like in other societies, the orientation of the constellations was used to mark seasons for harvesting or sowing crops. Certain constellations were noted for their yearly rising or setting times, and provided an accurate clock by which time could be measured. The Babylonians kept written records of calendars used for planting.

Babylonian Records

Babylonians kept records on clay tablets using a type of writing called cuneiform. At first this was generally for business purposes, in order to keep track of financial transactions and inventories. Several cuneiform tablets have been found, however, that focus on more scientific topics. One notable example is the Venus Tablet of King Ammizaduga, pictured below, which demonstrates the scientific methodology used by the Babylonian astronomers. The main topic of this tablet is the appearance and disappearance of the planet Venus as it goes from being an evening star to a morning star. Based on the detailed astronomical patterns mentioned in this tablet, modern scientists were able to use computers to determine that the Venus tablet was probably written in the year 1581 B.C. Another astronomical cuneiform tablet was found in the tomb of King Ashurbanipal of Ninevah, and also details the times of Venus' appearance and disappearance from the horizon.

Venus Tablet of King Ammizaduga

Scientific Breakthroughs

The Babylonians not only recognized Venus as the same object whether it appeared in the morning or evening, but they actually developed a method for calculating the length of the Venus cycle! According to the Babylonians, the length of one cycle was 587 days, compared with the actual value of 584 days. The slight difference is due to the fact that they attempted to coincide these astronomical cycles with phases of the moon.

Both the Babylonians and the Assyrians were able to predict lunar eclipses. They applied a simple method which made future predictions based on past observations. Several cuneiform tablets list series of lunar eclipses and mark time between successive events.

One of the major breakthroughs of the Babylonians was their invention of the degree system to distinguish positions in the sky. The system was similar to our use of degrees to calculate latitude and longitude. The Greeks adopted the degree system and also many of the Babylonian constellations, which they renamed in Greek.

REFERENCES FOR THIS PAGE:

Anthony Aveni, Stairways to the Stars, John Wiley & Sons, 1997.

J. Norman Lockyer, The Dawn of Astronomy, MIT Press, 1894.

SOURCE

Blossom of Mesopotamian astronomy falls on the I thousand of years B.C. In 612 B.C. the capital of Assiria (Ninevia) was ruined by the babylonian troops. Later an archaeologists found a lot of earthenware "books" of assirians priest-astronomers in the ruins of the palace of the last assirian tsar Ashurbanipal. There was a result of all forecoming development of astronomy. Apart from catalogue of stars and constellations and their morningrise data list those "books" included a list of" constellation in the Moon way", that is 18 constellations - a prototype of modern zodiac.
 

Messopotamia was covered by the net of temples, where they carried astronomical investigations. From the VIII-th century B.C. astronomers began to registrate the dates of observed Moon eclipses in special lists. Just the knowledge about ancient eclipses allowed Gipparch, Ptolemei and Copernic calculate with more accuracy the year duration.

These ancient scientists observations are actual even nowadays but there is understandment of lack of accuracy in their measurement in detecting distance between the Sun and the "basic" stars. There main astronomical tool was a water watch. Mesopotamian astronomers divided a day (24 hours) into 12 hours and every hour was divided into 30 "time degrees". One time degree had four our minutes.

Zodiac circle of assiriansThe most outstanding achievement of mesopotamian astronomy became the development of mathematic theory, helped to foremeasure the Moon and the planet moving with exactness enough for the naked eyed measurements.

During this epoch on a basis of long time observations it was discovered saros (Greek "repetition") i.e. 18-year period of the repeated Moon eclipses. It was also found the periodical law-governed nature of the planet movement. The classical scientists used the achievements of mesopotamian science.

Crude Celestial Concepts
(Source: S. Toulmin and J. Goodfield. The Fabric of the Heavens)

In any case, to be honest, we do not know for certain whether the astronomers had any theoretical
ideas about the heavenly bodies or not.  All we can say is that their practical achievements did not
require any theoretical insight, and that scarcely a trace has survived of any theories they may have
had.

One of the rare pieces of evidence, and a very indirect one at that, is contained in the following
passage from Vitruvius.  He reports a tradition that Berossos, a priest of Bel (i.e. Marduk), migrated
to the island of Cos (c. 290-270 B.C.E.) and lectured on Babylonian science.  Amongst other things he
taught a doctrine about the cause of the phases of the Moon.  At first sight this may seem to
discredit our generalization about Babylonian astronomy—namely, that it was purely
computational, and that theoretical speculation played a negligible part.  On closer examination,
however, the passage rather seems to bear out rather than to falsify this claim; for the theory put
forward is, by Greek standards, amazingly primitive:

Berrossos, who came from the city or nation of the Chaldeans and expounded Babylonian science in
Asia Minor, taught as follows:

The globe of the Moon is luminous on one hemisphere, the other half being dark blue in color.
When in the course of its journey it comes below the disc of the Sun, the rays of the Sun and its
violent heat take hold of it and on account of the properties of light turn the shining half towards that
light.  But while those upper parts look towards the Sun, the lower part of the Moon, which is not
luminous, is indistinguishable from the surrounding atmosphere and so appears dark.  When it is
quite perpendicular to the rays, all its light is retained on the upper face, and then it is known as the
first [or new] moon.

When, moving on, the Moon travels towards the eastern parts of the sky, the action of the Sun on it
weakened, and the very edge of its luminous hemisphere casts is splendor on the Earth in the form of
a very thin arc; from which it is called the second moon.  Moving round day by day, it is called the
third moon, fourth moon and so on.  On the seventh day, the Sun being in the West, the Moon
occupies the middle of the visible sky and, being half-way across the sky from the Sun, turns half of
its shining face towards the Earth.  But when on the fourteenth day the whole width of the heavens
separates the Sun and the Moon, the Moon rising in the East just as the Sun sets in the West, the
Moon is at that distance free of the effects of the Sun's rays and shows the full glory of its whole
sphere as a complete disc.  During the remaining days until the completion of the lunar month it
diminishes daily, turning as it comes once more under the influence of the Sun's rays, and so
effecting the days of the month in due order.
 

This explanation ignores half a dozen theoretical advances made by Greek thinkers in the two
centuries preceding 270 B.C.E.  So long as we think of the Sun and Moon as going round closed
orbits, we can immediately attribute these phases—as the Greeks did—to the changing angle at
which the Moon reflects the Sun's light.  But Berossos does not even recognize that the Moon's light
is borrowed; and his whole picture supposes that the two bodies go in straight-line paths at different
heights across the sky above the flat Earth.  If we retain the traditional picture—reminiscent of
Enuma Elish, with its:

                    ‘open gates on both sides
          With strong locks to the East and to the West'

we can understand Berossos' theory.  But, to a Greek, it must have seemed terribly crude.

SOURCE

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