Chinese astrology has a close relation with Chinese philosophy (theory of the three harmony, heaven, earth and water) and uses the principles of yin and yang and concepts that are not found in Western astrology, such as the wu xing teachings, the 10 Celestial stems, the 12 Earthly Branches, the lunisolar calendar (moon calendar and sun calendar), and the time calculation after year, month, day and shichen (時辰).