Did the Sumerians measure precession? (Intermediate)

I do understand Procession and the fact that it takes approximately 26,000 years to complete one full cycle. My question is:-
1. How is this measured with modern equipment.
2. How were the Sumerians in 3800 BC (modern day Iraq) able to quantify this in their ancient texts, which I understand there are many directly related to astronomy.
I was a little dumb struck when this was suggested and have since been convinced it's true.

The basic way to measure precession is to make accurate observations of the positions of fixed celestial objects over time. Hipparchus was the first person (at least where it is generally accepted) to have measured precession (in 134 BC). It is common to fix the position of stars relative to the point where the Sun crosses the celestial equator on the Autumnal Equinox (the day when there is exactly 12 hours of sunlight). Hipparchus noticed that the position of stars relative to this point had moved between his measurements and some similar measurements he had records of from 150 years previously. He reasoned that this must mean that the point of the equinox had moved and attributed this to the precession of the sphere of the stars (the Earth was fixed in his day). More modern measurements are exactly equivalent, but we can just measure positions more accurately now.

There are some claims that the Sumerians also measured precession, but I don't believe that they are commonly accepted. It seems to be based on the fact that they counted in multiples of 60 and that the length of the precession cycle is 26,000 years which is about 60*1200*360/1000 years. The 1200 and 360 also have some significance in Sumerian culture - interestingly the Sumerians gave us the degree (360 in a circle - they also had 360 days in their year) and the second/minute (there being 60 of them is no coincidence).


This page was last updated on June 27, 2015.

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Karen Masters

Karen Masters

Karen was a graduate student at Cornell from 2000-2005. She went on to work as a researcher in galaxy redshift surveys at Harvard University, and is now on the Faculty at the University of Portsmouth back in her home country of the UK. Her research lately has focused on using the morphology of galaxies to give clues to their formation and evolution. She is the Project Scientist for the Galaxy Zoo project.

Twitter:  @KarenLMasters
Website:  http://icg.port.ac.uk/~mastersk/

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