Bharatiya Jyotihshastra (History of Indian Astronomy), translated by R. V. Vaidya v1.c6.5

v1.c6.5

The planets appear to move from west to east with respect to the stars and in the science of astronomy this kind of planetary motions have principally to be dealt with. The *Sūrya-Siddhānta* has explained this eastward motion of planets as follows :—