How to calculate leap month? Calculation method of leap month

Lead: According to the composition of Chinese lunar calendar, the lunar year is actually shorter than the tropic year of the earth. Therefore, if calculated according to the lunar calendar 1 year1February, the Spring Festival will not be in winter but in summer after more than ten years. Therefore, a leap month was established. So how to calculate leap month? Let's look at the calculation method of leap month.

How to calculate leap month?

China's lunar calendar is a combination of yin and yang, and leap month refers to adding months and dates to the calendar, so that the average length of the calendar year is close to the tropic year. The lunar calendar arranges the big moon and the small moon according to the full moon. The length of a moon is 29.5306 days, which is the cycle of the moon's profit and loss. According to the lunar calendar, the big month is 30 days, the small month is 29 days, and a year is 12 months. These twelve moons constitute the Han calendar year, with a length of 29.5306× 12 = 354.3672 days, which is less than the tropical year's 365.2422 days 10.88 days (that is, nearly 1 1 day), with a monthly decrease of 0.9/kloc.

In this way, if after 17, the date of the lunar calendar will be reversed in the same season. For example, a year's New Year is spent in the snow, and after 17, the fans will be shaken for the New Year. Using such a calendar naturally cannot meet the needs of agricultural production. Therefore, since the Qin and Han Dynasties, the lunar calendar in China has been in parallel with the twenty-four solar terms, which are used to guide agricultural production.

But if the lunar year consists of thirteen moons, the length is 29.5306× 13 = 383.8978 days, which is 18 days more than the tropic year. If the calendar is made according to the above regulations, there will be a strange phenomenon that the weather is inconsistent with the calendar and the time order is disordered and reversed. This is the contradiction.

Therefore, in order to overcome this shortcoming, our ancestors found out the method of "leap month" on the basis of astronomical observation, ensuring that the first month to March is spring, April to June is summer, July to September is autumn, and October to December is winter, and at the same time ensuring that the first year of the lunar calendar is in late winter and early spring (all above refer to lunar season).

Calculation method of leap month

So what do you think of the lunar leap month? It depends on the 24 solar terms in a year.

The lunar calendar takes the moon as the cycle (lunar calendar), and the December calendar is about 354 days. Combined with the almanac (solar calendar), the almanac is compiled according to the four-season cycle formed by the revolution of the earth. The monthly calendar is shorter than the annual calendar by 1 1 day. Therefore, it is necessary to add 7 leap months every 19 years to make up for the error.

Which month is a leap month depends on 24 solar terms. Lunar months usually include a solar term and a neutral atmosphere, such as the vernal equinox. If a lunar month has only solar terms and no neutral atmosphere, the calendar will take that month as the leap month of last month. Take 2006 as an example. After July of the lunar calendar, there happens to be a month with only solar terms and no neutral atmosphere, so we set leap July to adjust the error.

The custom of leap moon

1, send parents "leap moon shoes"

"Leap-moon shoes are worn in leap months, and the elderly in leap months live 1000 years old." In some local folk customs, every leap year and leap month, children should buy a pair of shoes for their parents to repay the kindness of parenting and pray for their parents' health and safety. In some areas, it is a leap month year, and married daughters have to buy shoes for their mothers.

2. Go back to your mother's house for a "leap moon meal"

"Leap Moon Rice" is also called "Six Parents Rice". Every year in the leap month of leap year, the bride's family will invite her married daughter home for dinner. Please when your parents are alive; If parents are not alive, brothers will invite them.

The bride's family gave her daughter an umbrella and a banana fan.

In some parts of our country, the bride's family will also send an umbrella and a banana fan to her daughter in leap month. It means that the bride's house is her daughter's umbrella. I wish her an early birth and make money for her husband's family.

The date of the twenty-four solar terms of the lunar calendar is postponed month by month, so in some lunar months, the gas falls at the end of the month, and it will be out of gas next month. Generally, there will be a month without gas every two years, which coincides with the year when leap months are needed. Therefore, the lunar calendar stipulates that non-neutral months are leap months.