An international team of researchers has reviewed the earliest reliable record of a total solar eclipse observed in ancient China in 709 BC. This made it possible to determine much more accurately the Earth's rotation rate almost three millennia ago. The work was published in the Astrophysical Journal (AJL).
Modern calculations for a long time gave a contradictory result: according to them, the entire eclipse phase could not be seen from the royal court of Lu, located in the city of Qufu. Scientists realized that the problem might not lie in mathematics but in geography and turned to archaeological data. It turns out that previous studies had used the wrong coordinates for ancient Qufu, missing it by about 8 km. After correcting the coordinates, the calculations coincided with the observations recorded in the chronicles.
This revision was key to more accurately determining how the Earth rotated in the 8th century BC. D. Changing the coordinates helps clarify the value of the parameter that characterizes the deviation of the Earth's rotation from uniformity. These data help refine previous models and clarify the timeframe of ancient astronomical events. The Earth actually rotates faster than it does today: a gradual slowing down due to the tidal friction of the oceans under the influence of the Moon.
The work shows how important ancient observations can be when combined with modern computational methods. The Chinese carefully recorded celestial phenomena because they considered them signs of their rulers, and these records continued to yield scientific discoveries thousands of years later. According to the authors of the study, the combination of ancient chronicles, archaeological data and modern calculations allows us to literally look into the past and restore the evolution of the Earth's rotation and solar activity with incredible accuracy.
