Research on the Motion of Mars in the Sovereign Pole System (a.d. 600)

The Sovereign Pole System (a.d. 600) is the first Chinese system to take account of the equation of centre for the sun and planets in the planetary theory. In this paper, we mainly discuss the motion of Mars in the Sovereign Pole System. First, we discuss the algorithm for calculating the time of Mars’ first appearance, especially we discuss the influence of the equation of centre for the sun and Mars at the time of Mars’ first appearance. Then, we discuss the segmented motion of Mars in one single synodic period and its accuracy. Finally, we discuss the method for computing the position of Mars at any given time and the error in longitude of Mars. The result shows that the innovations in planetary theory found in the Sovereign Pole System were a fruitful development in ancient Chinese planetary theory and it obviously improved the accuracy of calculation of the position of Mars. However, the planetary theory in the Sovereign Pole System is still relatively rough because it was impossible for Sui astronomers to obtain the correct model of the motion of planet.