Why isn't Tomb-Sweeping Day based on the lunar calendar?

There are many problems. Tomb-Sweeping Day is one of the 24 solar terms. A year is divided into 24 solar terms according to the movement of the sun and several months according to the movement of the moon. Twelve miscarriages and big months add up to only 354 or 355 days. Compared with the two, the difference is about eleven days. In order to coordinate the two, the ancients adopted the method of "fixed leap", and one year in several years was thirteen months (leap month). Our 24 solar terms are not based on the lunar or solar calendar. Strictly speaking, they are based on the longitude of the sun. The path of the sun under the starry sky background is called the ecliptic. When the sun moves to the longitude of 0 degrees, it is the vernal equinox, which is a solar term of about fifteen days. By analogy, "Qingming" is when the sun moves to longitude 15 degrees. Because of the leap year, the date of solar terms will change, but the date difference will only be within three days, and the date in Tomb-Sweeping Day will be between April 4th and 6th in the Gregorian calendar. For example, April 5th is in Tomb-Sweeping Day this year, and April 4th is in Tomb-Sweeping Day in 2009. Other traditional festivals, such as Dragon Boat Festival, Mid-Autumn Festival and Spring Festival, are based on the lunar calendar, so the Gregorian calendar dates vary greatly every year.

Because the 24 solar terms objectively reflect the changes of temperature, rainfall and phenology throughout the year, ancient working people used them to arrange agricultural activities. Qingming is on the fifteenth day after the vernal equinox. "When everything grows, it is clean and clear, hence the name Qingming." As soon as Qingming arrives, the temperature rises and the rainfall increases, which is a good season for spring ploughing and sowing. Therefore, there are agricultural proverbs such as "before and after Qingming, plant melons and beans" and "planting trees is not as good as Qingming".

Among the 24 solar terms, only Qingming is both a solar term and a festival. "Tomb-Sweeping Day" is not only a day to worship ancestors and sweep graves, but also called "Walking Festival". At this time, it is the season of bright spring and lush vegetation, which is suitable for people's spring outing. In ancient times, there was a cold food festival the day before in Tomb-Sweeping Day. According to legend, it was pushed by the sage meson of Jin State in the Spring and Autumn Period. On the day of cold food, no fireworks were moved, only cold food was eaten. Later, with the passage of time, cold food and Qingming gradually merged into one, and even cold food in most places became another name for Qingming.

Tomb-Sweeping Day is a solar term in the lunar calendar, and it also conforms to the Gregorian calendar. The setting and calculation of this festival once again embodies the science and wisdom of our ancients. Tomb-Sweeping Day is based on the Gregorian calendar, and sometimes there is no 10 10 30th in the lunar calendar, because the lunar calendar has a big moon and a small moon, with 30 days, but no abortion with only 29 days. Tomb-Sweeping Day is on the third day of the third lunar month, 90% of which is every 19 years, and the Gregorian calendar and the lunar calendar date are the same day. Not necessarily 19, some people may be 38 years. In short, multiple years of 19 will definitely be blocked!

But there are also 38 years.

Some people are 57 years.

This situation is mainly the result of the leap of the lunar calendar. 19 Why is there a coincidence? The number of days in each month in the lunar calendar is determined according to the cycle of the moon. In fact, the average number of days per month is 29.5306. If multiplied by 12, there are only 354.3672 days in a year. One revolution of the earth around the sun (tropical year and solar year) is 365.2422 days, so the lunar year 1 the actual number of days is less than that of the sun 10.875 days, almost 1 1 day, 19 is 209 days less.

209 days divided by 30 is 6.9666, that is to say, 19 years, the lunar calendar is almost 7 months shorter than the solar calendar. In order to make the difference between the lunar calendar and the solar calendar not too much, it is necessary to make up these seven months.

China's lunar calendar is actually a typical lunar calendar, which is formulated in consideration of the movement cycle of the moon around the earth and the movement cycle of the earth around the sun. In order to make up for these seven months, people adopt the method of setting leap months in the lunar calendar-seven leap months in nineteen years, that is, nineteen years of the lunar calendar, and 12 is a normal year, every 65438. Plus seven leap years (3, 5, 8, 1 1, 14, 17, 19), every 1 leap year has 13 months.

In this way, the number of days in the 19 solar year is almost equal to the number of days in the 19 lunar year. Therefore, whenever the birthday is 19 or 19 times the age, there is a chance that the solar calendar and the lunar calendar will be on the same day.