Ancient Babylonian Astronomy and Celestial Knowledge
Ancient Babylonian Astronomy: A Legacy of Celestial Observation
The Dawn of Babylonian Civilization
With the decline of Egypt, significant developments occurred in Mesopotamia, leading to the construction of great buildings. Around 1800 BC, the culture of Babylon began to flourish. By 1755 BC, the Code of Hammurabi, a foundational legal text covering criminal and commercial matters, was established.
Evidence suggests cultural relations between Egypt and Mesopotamia. For instance, a trace of King Djet, dated to 2370 BC, was found in the Arabian Desert, attesting to the ancient contacts between Egyptians and Mesopotamians.
Ziggurats: Observatories of the Ancient World
In the clear atmosphere of Mesopotamia, astrology developed into a form similar to what we recognize today. For over five millennia, the priest-astrologers of Babylon dedicated themselves to studying the sky and identifying all visible stars. To facilitate this, they constructed observatories on the plains, known as Ziggurats. Such monuments date back to as early as 2600 BC.
Babylonian Astronomical Records and Calendars
Documenting Celestial Events
Small cuneiform tablets from the Library of Nineveh reveal insights into Babylonian and Chaldean astronomy and astrology. They also recorded the passage of Halley's Comet in 164 BC.
The Soli-Lunar Calendar System
They utilized a soli-lunar calendar with twelve or thirteen months, each approximately 29.5 days long. These months began with the first visible crescent moon. The Babylonian year commenced in early spring. They were, of course, aware of each of the visible planets and their cycles.
Understanding Lunar Cycles
Another significant cycle observed by the Babylonians was derived from the Moon's phases. This lunar cycle was arguably the most important and widely used. The approximately 28-day lunar cycle was divided into four parts, corresponding to the four main phases of the Moon: new, waxing crescent/first quarter, full, and waning crescent/last quarter. These four points marked critical junctures within the lunar month.
Mastering Eclipses and Celestial Measurement
No astronomical phenomenon was overlooked, especially eclipses. Their knowledge of eclipses was so advanced that it could be used as a strategic tool, a practice later adopted in Greece. The Babylonians understood a sophisticated pattern known as the Saros cycle, which predicts repetitive eclipse occurrences. This understanding necessitated precise celestial measurement.
They calculated how many lunar or solar cycles were needed to complete a full measure of the heavens, identifying 360 'steps' or divisions in the sky. This celestial measurement led to the division of the circle into 360 degrees and formed the basis of their sexagesimal (base-60) number system.
The Intertwined Worlds of Astronomy, Mathematics, and Religion
During this era, mathematics, astronomy, and religion were not separate disciplines but formed a single, integrated body of knowledge. Astrology served as the synthesis of this powerful trilogy.
For this ancient civilization, a profound relationship existed between human life and the position of celestial bodies at the time of birth. Therefore, it was crucial to know which star or constellation was rising at that precise moment. This gave rise to positional astronomy. Unlike the later Greeks who sought geometric explanations, the Babylonians developed a methodical, arithmetic approach to predict the position of any celestial body at a given time. This led to the development and use of ephemerides (tables predicting celestial positions), underscoring that Mesopotamian astronomy was primarily astrological and based on positional arithmetic. The extensive knowledge of the Chaldeans was later transmitted to and built upon by the Greeks.