Ancient Chinese eclipse record reveals Earth's rotation speed

An international team of researchers has used a solar eclipse recorded in 709 B.C. to calibrate the Earth's historical rotation speed. The event was documented by scribes in the ancient Duchy of Lu, China, and preserved in historical chronicles such as the ‘Annals of Spring and Autumn’ and the ‘Hanshu’ (Book of Han).

Initially, modern astronomical models showed a discrepancy, suggesting the eclipse's path of totality should not have been visible from the ancient capital, Qufu. However, by utilizing archaeological data and historical cartography, scientists corrected a geodetic location error of eight kilometers. This adjustment allowed for a precise reconstruction of the eclipse's orbital trajectory.

The study, published in The Astrophysical Journal Letters, also highlights a description in the ‘Hanshu’ that scientists believe may be the oldest written record of the solar corona, the Sun's outer atmosphere.