Astronomy of Mesopotamia: Sumeria, Babylon,
|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
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
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
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.
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.