This paper examines the three phases of Greek astral sciences introduced to China by the Nestorians, Perso-Arabs and the Jesuits. Though ultimately springing from the same sources, largely based on the works of Ptolemy and his contemporaries, who have established themselves as authority in the subject in Western Europe and the Byzantine Empire from the middle of the first millennium for over a thousand years, the Greek science practiced and brought by these foreigners carried unique characteristics of their own. As the cosmologies encapsulated in these works as well as the accompanying scientific concepts and techniques were drastically different from those of the indigenous Chinese, each of these “foreign waves” left a different impression in the Chinese world, with different degrees of impact which can be observed both historically even today. Some of the legacies of these ongoing dialogues between the Greek and the Chinese can be seen in the East Asian planetary week, the Zodiac, and a myriad of hybridized forms of genethlical astrology.