How did Qingming determine the date?

Astronomically speaking, when the sun reaches 15 degrees on April 5 or 6, it can be designated as Qingming.

Tomb-Sweeping Day is a Gregorian calendar date, which is fixed between April 4th and April 6th every year in the Gregorian calendar. One revolution of the earth is 360 degrees of the yellow meridian, and when the earth reaches zero degrees of the yellow meridian, it is designated as the vernal equinox, and then there is a solar term every time it runs 15 degrees, and there are 24 solar terms in * * *. Therefore, the dates of solar terms in the solar calendar are fixed, because leap years differ by at most two days.

The dates of solar terms are relatively fixed in the solar calendar. For example, beginning of spring in the solar calendar always falls between February 3rd and 5th. However, in the lunar calendar, the date of solar terms is not easy to determine. Take beginning of spring as an example. It can be the first day of the lunar calendar in the previous year, 65438+February 15, and the latest is the first month, 15. Tomb-Sweeping Day is usually between April 4th and June in the Gregorian calendar, but it cannot be based on the determined lunar calendar date.

Dietary customs in Tomb-Sweeping Day

In addition to various folk customs, such as grave-sweeping, outing and so on, some diets in Tomb-Sweeping Day are also quite distinctive. In some places, there is a custom of eating "descendants swallows", that is, when worshipping ancestors, many steamed buns will be steamed and made into the shape of swallows, which will be distributed to children after the sacrificial ceremony to welcome the arrival of spring.

In ancient Tomb-Sweeping Day, people also ate eggs, which was very similar to Easter in the west. Eggs also mean a life form. Some places in the south will eat "green balls", that is, the juice of wormwood or other edible grass is mixed with glutinous rice and steamed. The green ball is delicious and fragrant, and it also means to ward off evil spirits. In addition to the above diet, "drinking porridge" is also one of the folk customs in Tomb-Sweeping Day. In order to adapt to the characteristics of hair growth in spring, people will add leeks, bean sprouts and other foods on this day.