Final answer:
Options A, B, C, and D were all measurements and observations that ancient astronomers made, such as monitoring the solstices, lunar cycles, and eclipses. Therefore, the correct answer is E, which states that all the provided options were indeed measurements made by ancient astronomers.
Step-by-step explanation:
To answer which of the following is not an example of measurements of ancient astronomers, we must look at the options: A. Marking the day of summer solstice, B. Measuring the 18.6-year cycle of lunar phases due to precession of its orbit, C. Measuring the orientation of the Crescent Moon, D. Measuring the time for eclipse seasons to repeat, and E. All the above were measurements made by ancient astronomers. Ancient civilizations such as the Babylonians, Egyptians, Greeks, and Chinese were advanced in their astronomical observations. They engaged in activities like keeping track of time and dates by observing celestial bodies, marking significant events like solstices, understanding the cycles of the moon, and studying eclipses to predict their occurrence.
The correct choice here is E. All the above were measurements made by ancient astronomers.