In the first year of Tai Chu (BC 104), Emperor Wu of the Western Han Dynasty issued a letter to taichu calendar, and the first month of the year was the beginning of the year, and the 24 solar terms were put into the calendar. This is the year when China officially established the first month as the beginning of a year.

Before that, although the calendar was revised many times, the beginning of the year was not fixed. The beginning of the ancient year was not fixed. Later, Emperor Wu of the Han Dynasty promulgated the "taichu calendar" and decided to take the first month of the lunar calendar as the beginning of the year. This system has been used by successive dynasties for more than 2000 years.

Historically, the revised taichu calendar in the Han Dynasty is of great significance, which marks the maturity of our calendar system. This calendar not only played an important role in agricultural production at that time, but also had a far-reaching impact on the calendar system of later generations.

Besides, there are many other traditional customs and meanings in the first month of the lunar calendar. For example, the Spring Festival, Lantern Festival and other festivals are all related to the first month, and people will celebrate during this time to pray for peace and happiness in the new year. At the same time, the first day of the first month is rooster day, and the second day of the first month is dog day. People will hold corresponding celebrations in these days. These traditional customs also have far-reaching significance in China culture.

The meaning of the calendar:

Calendar provides accurate time for people, which is of great significance to agriculture, industry, transportation, communication and many other aspects. In modern society, calendars can also accurately predict astronomical phenomena such as solar eclipse, which provides important reference for people's production and life.

2. Calendar can provide people with knowledge and understanding about time and deepen people's understanding of nature. Calendar is also an indispensable part of scientific research. For example, by modifying and perfecting the calendar, the distance and motion law of stars can be calculated more accurately, which is of great significance to the research in astronomy, physics and other fields.

3. Calendars also have cultural significance. Different calendars represent different cultural traditions and historical backgrounds. The revision of the calendar can also reflect the cultural characteristics and historical background of different periods, such as the 24 solar terms in China, Christmas in the west and other traditional calendars, which are all important heritages of human culture.