Study on Secular Change of the Earth’s Rotation Rate Based on Solar Eclipse Observation Records on October 13, 443 BC

ABSTRACT An observation of a solar eclipse that occurred on October 13, 443 BC during the reign Duke Ligong Qin was recorded in Twenty-Four Histories (China’s dynastic histories from remote antiquity till Ming Dynasty). With modern astronomical planetary ephemeris, records were studied. The results showed probably around sunset Yongcheng, capital Qin, where time exactly between first contact stage (partial begins) and fourth ends) eclipse. Furthermore, secular change earth’s rotation rate at is investigated this work.