Why did you change your zodiac in the spring?

To answer this question clearly, we have to start with the traditional calendar and the year of the main branch in China.

The traditional calendar in China is now called "Lunar Calendar", which follows the taichu calendar Law of Han Dynasty (namely "Han Calendar") and belongs to the calendar of combining Yin and Yang.

The solar calendar is based on the solar calendar, and the main body is the 24 solar terms. As early as the Spring and Autumn Period and the Warring States Period, China people have measured the length of the midday sun shadow with a sundial to determine four solar terms: winter solstice, summer solstice, vernal equinox and autumn equinox. The history books of the Spring and Autumn Period recorded the solar terms. By the end of the Warring States Period, there were eight solar terms, such as beginning of spring, Equinox, Long Summer, Summer Solstice, beginning of autumn, Equinox, beginning of winter and Winter Solstice. Huainanzi (BC 139) in the Western Han Dynasty recorded the 24 solar terms completely. In BC 104, the taichu calendar written by Deng Ping officially set 24 solar terms in the calendar, and defined the astronomical position of the 24 solar terms.

In the lunar calendar, the month is determined by the moon. At the beginning of each month, the sun and the moon rise at the same time, and there is no "new moon" of the moon on the earth. The length of each month may be 30th or 29th, 12 months is a year. Odd numbers, such as 1, 3, ... Among the 24 solar terms in the solar year, 23 are knots, and the second, fourth and ... 24 are qi or neutral qi. Because the solar annual cycle is inconsistent with 12 months with the moon phase as the cycle, the month without neutral gas is set as leap month, and the number is the same as last month, which is called leap month. 2012 may 21-June 18 is leap April, during which there are only ear festivals.

Every dynasty in history has to "establish the moon", that is, to determine when the first new moon day of the year is. This is to say "chronology of branches", that is, a chronology of ten branches and twelve branches every sixty years.

It is now recognized that the first Jiazi was in 2697 BC. On the winter solstice that year, the Yellow Emperor ascended the throne, and ordered the minister to make a big statement, starting with "Jiazi" and marking the year as the first year of the Yellow Emperor. At the end of the Warring States Period, Shi Ben said: "Rongcheng is the calendar, and the big spoke is Jiazi."

The chronological method of trunk and branch takes the month of winter solstice as the next month, followed by the other twelve branches. Each branch corresponds to 24 solar terms from one solar term (non-China spirit) to the next, and the starting period is determined by the time of solar terms.

In the Xia Dynasty, the winter solstice, the sun and the moon were used as calendars, starting from one year old, but "Zhengshuo" started in silver moon, that is, "Andrew". Xia Hou, Shang and Zhou Dynasties advanced the "Zhengshuo" to the ugly month and the next month respectively. It was not until Emperor Wu of the Han Dynasty formulated the taichu calendar that the original month order of the Xia calendar was restored, and it has been used ever since.

Now, more complex calendars all show the 24 solar terms of a year, the lunar calendar and the solar calendar, as well as the month and date of the year. Put them together and you can see the difference.

Let's talk about the zodiac again.

It is generally believed that Lun Heng (AD 86) written by Wang Chong in the Eastern Han Dynasty is the earliest record of the zodiac. "On the Balance of Things" contains: "Yin, wood, birds and tigers. Soil, its birds and dogs are also. ..... At noon, the horse also arrived. Son, mouse also. Unitary, chicken also. Hair, rabbits, too. ..... hey, tapir. No, so are sheep. Ugly, cattle also. ..... Third, snakes are also. Shen, Qitian also. " There are only eleven zodiac signs in the above quotation, but the dragon is missing. The book "Poisonous Words" also said: "Chen Weilong, Si is a snake, and Chen and Si are in the southeast. In this way, the zodiac is completed.

Obviously, there is yin first, then there is tiger. Zodiac varies from place to place, and heavenly stems and earthly branches rises with the change of solar terms.

To sum up, according to the Han calendar that has been used to this day, the first day in silver moon where beginning of spring is located is designated as the first day of the first lunar month, and we celebrate the New Year. Because the beginning of the solar year and the lunar year are not exactly the same, unless the first day of the first month is beginning of spring (for example1992,2038), then the zodiac will follow the earthly branches and beginning of spring sooner or later!