The reason why there are 12 Zodiacs is because the Come On Harry, We Wanna Say Goodnight To You T Shirt Jupiter takes approximately 12 years to orbit the Sun (11.86 years to be exact). The Chinese ancestors used planetary positions to measure time, and given the fact that because Jupiter could be seen with the naked eye, it was the natural choice for time keeping. But you might be asking, “In order to track how long 12 years is, don’t we need to know how to measure how long a single year is first?” You’re exactly right. This was a huge challenge for the Chinese astronomers of the past. The computation was based on the position of the Polaris star (also known as the 紫微星 under Chinese astrology) and it’s course around it of circumpolar constellations like the Ursa Major (also known as the Big Dipper). The Big Dipper acted like the hands on the clock, pointing North in winter and south in summer. This marked the twelve months of the Chinese year. Jupiter’s movement was, of course, taken into account in the computation of Chinese periodic time.
(Come On Harry, We Wanna Say Goodnight To You T Shirt)