What are the Origins of Astronomy

Astronomy has often been seen as a field first developed by ancient Greek scholars, but its origins most likely stretch back to recorded history. We know that astronomy has played a vital role in the agricultural cycle and early religions. These early innovations have led to major advancements in developing our calendar, a system of time, understanding of astronomical movements and prediction, coordinate system, and mathematical developments.

Early Development

Most likely, astronomy developed when agriculture becomes significant in the Neolithic in the ancient Near East. However, we only learn about astronomy in the 3rd and particularly in the 2nd millennium BC. By this time, astronomy had developed to regulate the agricultural cycle; however, perhaps more significantly for ancient Mesopotamian societies, it was used to create a calendar utilized in the worship of gods.

In effect, much of the learning that had to do with understanding the movement of celestial bodies was generally conflated with astrology. The signs of the zodiac were invented in Mesopotamia probably by the 3rd millennium BC. Specifically, this occurred in southern Mesopotamia, a region that eventually became synonymous with Babylonia and, by extension, the Babylonians, who provided much of our knowledge of how ancient astronomy developed there.

The first astronomers were priests responsible for recording their observations on cuneiform tablets (Figure 1). Their observations were utilized as signs from the gods. That information was then interpreted to understand events that might affect the king and his kingdom.

Although on the surface, these seem to be nothing more than a system of superstition, the nearly continuous observation, over many centuries, of the celestial bodies led to subsequent developments that have influenced our scientific progress in the area.

Major Achievements

Cuneiform Tablet detailing Halley's Comet from 164

Humans developed systems to understand where specific bodies, i.e., stars, moons, planets, comets, and asteroids, would interpret and provide omens to their information to their communities to both understand the past and predict the future.

This led to creating a calendar that would be timed around the movement of the moon in particular and a system to predict when specific events would occur, such as eclipses. The eventual calendar that emerged began to have features we now also have in our calendars.

The calendar was based on the lunar cycle and the rotation of the Earth around the Sun, thus a form of a lunisolar calendar, giving the calendar 12 months, with the name of the months still used in Arabic and other Near East calendars. Leap months were utilized to make up for the shortfall in days for a given year. Because the Babylonian calendar was relatively accurate, many historical events recorded in their calendar could be dated to the exact day in some instances. For instance, we know the exact time Halley’s comet was observed for the first time (Figure 1). While Herodotus is often called the first historian, the Babylonians should have this title more accurately as they provide the first set of accurate ancient dates anywhere in ancient history.

Other achievements include the understanding that solar and moon eclipses occur in periodic cycles that can be predicted. This eventually led to the system we call the Saros system, a system still used to predict eclipses. The world Saros derives from an Akkadian (i.e., the language used in much of Mesopotamia) word. In general, the system used by Mesopotamians, specifically the Babylonians, to calculate lunar orbit was considered highly accurate.

Additional innovations include the idea that the sky can be divided into coordinates using 360 degrees. This invented a coordinate system used for any spatial mapping, which is a system we still use. In Mesopotamia, a sexagesimal system for counting and recording numeric data such as coordinates made keeping track of location convenient. This also works well for a time. This Mesopotamian sexagesimal system is what we have inherited for use in the measurement of time while also using the Babylonian system in our own coordinate systems.

Conclusion

The need to keep track of time, record the location of celestial bodies in a type of coordinate system, and predict when events such as eclipses would occur meant that in Mesopotamia, geometry had to be well developed. By at least the 2nd millennium BC, people already understood the measurement of angles, the Pythagorean theorem (i.e., long before Pythagoras lived; Figure 2), and measurement of circular surfaces. As an example, the Babylonians had already known that Pi was slightly greater than 3.1 in value.

References

Updated December 15, 2018. Admin and Maltaweel