The correct division of the zodiac is the time of solar terms on the day of spring. The Spring Festival (the first day of the first lunar month in the lunar calendar) is just a popular calculation among the people nowadays.
There are actually two kinds of calendars in ancient my country. One is based on the movement of the moon, which is the "lunar calendar"; the other is based on the movement of the sun, which is the ancient "solar calendar". The twenty-four solar terms are determined according to the movement of the sun. The beginning of spring is the first day of the new year in the ancient solar calendar. The twelve zodiac signs (called the twelve earthly branches in ancient times) are determined according to this and have nothing to do with the lunar calendar.
In addition, in addition to the zodiac signs (earthly branches) for the year, the month, day, and hour all have corresponding zodiac signs (earthly branches). (It should be noted that this "month" is also demarcated according to the twenty-four solar terms. , not the month of the lunar calendar). For example, at the beginning of spring, the Waking of Insects screams Yin Yue (tiger), and from 11 pm to 1 am, it screams Zi Shi (rat).
So everyone actually has four zodiac signs: year, month, day, and hour!
Each earthly branch (Zi, Chou, Yin, Mao...) of the year, month, day and hour will have a corresponding heavenly stem to match according to the calendar (***Ten heavenly stems: A , B, C, D...), so that each person has eight characters, which is the origin of the ancient "birthday eight characters".
Also, everyone should know that the current Spring Festival (the first day of the first lunar month in the lunar calendar) was called "New Year's Day" before the Republic of China. It was Yuan Shikai who changed "New Year's Day" to January 1 in the Gregorian calendar. The first day of the first lunar month was renamed "Spring Festival", and the ancient Spring Festival specifically refers to the day of the beginning of spring. The beginning of spring and the Spring Festival were the same day before the Republic of China.
So after the changes during the Republic of China, the Republic of China inherited the Western Yuan calendar (Gregorian calendar) as the calendar from the Republic of China, including major changes to the Spring Festival and New Year's Day. In the past hundred years, the algorithm of zodiac signs has changed. It's completely confusing. Nowadays, perhaps only the older generation and those who know the birth dates and horoscopes know the correct calculation of the zodiac signs.
If you were born on the Beginning of Spring, the first step is to find out on the perpetual calendar the time of the solar term on the Beginning of Spring in the year of birth; the second step is to know your place of birth and the accurate birth date. Time, the above two items can be converted to the true solar time of your birth on some websites (the original one is just Beijing time); the third step is to compare the two times. The one earlier than the solar term time is the zodiac sign of the previous year. On the contrary, it is the zodiac sign of the following year.
....so complicated!