"Huainanzi Astronomical Training" records: "On the fifteenth day after the vernal equinox, when the handle of the Big Dipper points to the second place, the wind will clear up." The "Qingming" solar term got its name. Qingming is one of the twenty-four solar terms in China, which was determined by the ancients according to the astronomical phenomena and the cycle of the four seasons.

Extended data

Tomb-Sweeping Day, also known as the outing festival, is at the turn of mid-spring and late spring. Tomb-Sweeping Day is a traditional festival in China, and it is also one of the most important sacrificial festivals. It is a day to sweep graves and worship ancestors.

Tomb-Sweeping Day is a traditional festival of the Chinese nation, which started in the Zhou Dynasty and has a history of more than 2,500 years. Through the development and evolution of history, Qingming has extremely rich connotations, and different customs have been formed in various places. Grave-sweeping and ancestor worship and outing are the basic themes.

Tomb-Sweeping Day is one of the important "eight festivals a year" in China. Generally, it is around April 5 of the Gregorian calendar, and the festival is very long. There are two sayings: 8 days before 10 and 10 days before 10, and these 20 days belong to Tomb-Sweeping Day.

Tomb-Sweeping Day originally meant grave-sweeping day, and the government of the Republic of China designated 15 days after the vernal equinox in 935 as a national holiday, also known as the national grave-sweeping day. Tomb-Sweeping Day, Dragon Boat Festival, Spring Festival and Mid-Autumn Festival are also called the four traditional festivals in China. Ancestor worship and outing are two major themes of Tomb-Sweeping Day customs. These two traditional customs and habits have been passed down in China for thousands of years without interruption.

References:

Baidu Encyclopedia-Tomb-Sweeping Day