Astrological sign operate on cycles of years, lunar months, and two-hour periods of the day (also known as "shichen"). A particular feature of the Chinese zodiac is its operation in a 60-year cycle in combination with the Five Phases of Chinese astrology (Wood, Fire, Metal, Water and Earth). Nevertheless, some researches say that there is an obvious relationship between the Chinese 12-year cycle and zodiac constellations: each year of the cycle corresponds to a certain disposal of Jupiter. For example, in the year of Snake Jupiter is in the Sign of Gemini, in the year of Horse Jupiter is in the Sign
Zodiac used to determine the boundaries of astronomical constellations that lie in the vicinity of the zodiac, which are, and always have been, irregular in their size and shape. The convention of measuring celestial longitude within individual signs was still being used in the mid-19th century, but modern astronomy now numbers degrees of celestial longitude from 0° to 360°, rather than 0° to 30° within each sign. The use of the zodiac as a means to determine astronomical measurement remained the main method for defining celestial positions by Western astronomers until the Renaissance, at which time preference moved to the equatorial