How did the lunar calendar in China come about? Why does it go backwards every year?
The 24 Solar Terms
In essence, solar terms belong to the solar calendar. From the astronomical point of view, the 24 solar terms are divided into 24 equal parts according to the 360-degree revolution of the earth around the sun (ecliptic), and the spring is divided into zero points. The two bisectors are separated by 15 degrees, and each bisector has a proper name, which contains the significance of climate change, phenological characteristics and crop growth. The twenty-four solar terms are beginning of spring, rain, surprise, vernal equinox, Qingming, Grain Rain, Long Summer, Xiaoman, Mangzhong, Summer Solstice, Slight Summer, Great Summer, beginning of autumn, Early Summer, White Dew, Autumn Equinox, Cold Dew, Early Frost, beginning of winter, Light Snow, Winter Solstice, Slight Cold and Severe Cold. In this order, all the single rooms are "solar terms", usually called "solar terms", while the double rooms are "neutral gas", referred to as "qi", collectively referred to as "solar terms". Now it is generally called twenty-four solar terms.
Twenty-four solar terms have been gradually established and improved in China. During the Zhou Dynasty and the Spring and Autumn Period in China, the summer solstice, winter solstice, vernal equinox and autumn equinox were determined by measuring the sun's shadow with soil gauge. Soil regression measurement is to measure the length of the sun shadow at noon with a vertical pole. The twelve solar terms recorded in Lu Chunqiu in Qin Dynasty have increased to eight, namely, beginning of spring, Spring Equinox, Long Summer, Summer, beginning of autumn, Autumn Equinox, beginning of winter and Winter Solstice. There are also some records about the germination of solar terms, such as stinging, rain, slight heat, white dew and first frost: 1 month. The stinging insects began to vibrate, and it began to rain in February, and the slight heat came in May, and the white dew fell in July, and it began in first frost in September. By the Han Dynasty, Huainanzi Astronomical Training had a complete record of 24 solar terms, exactly the same as today.
There is a folk song in our country:
Spring rains shake spring and clear valleys,
Summer is full, summer is full, summer is summer,
Autumn dew and autumn frost,
It snows in winter, it snows in winter, and it's a little cold in winter.
In order to remember the order of the 24 solar terms, people each took a word and made it up.
The length of the calendar month in the lunar calendar is subject to the first month of the lunar calendar, with 30 days in the first month and 29 days in the second month. The first lunar month and the second lunar month complement each other, making the average length of calendar months close to the first lunar month.
Lunar New Moon is the first day of the month-the first day of the month. Astronomically speaking, the so-called "new moon" has a definite moment, that is, the ecliptic of the moon is the same as that of the sun. (The calculation of the ecliptic of the Sun and Moon is very complicated, so I won't introduce it here. )
As for the basis for determining the name of the lunar month, it is determined by "Zhongqi". That is, the month containing "rain" is January; February is a month with "vernal equinox"; March is the month of Grain Rain; April is a month with "small fullness"; May is the month of "summer solstice"; June is the month of "great summer heat"; July is the month of "summer heat"; August is the month of autumnal equinox; September is the month of "first frost"; 10 is the month of "light snow"; 1 1 month is the month of "winter solstice"; 1February is a "cold" month. There is no month with neutral gas like last month's leap month.
The calendar year of the lunar calendar is based on the tropic year, but a tropic year is more than 12 months and less than 13 months. When ancient astronomers compiled the lunar calendar, in order to make any day in a month contain the meaning of the moon phase, that is, the first day is moonless night and the fifteenth day is full moon, with the moon as the main factor, taking into account the seasons. There are seven leap years and each leap year has thirteen months.
Why adopt the method of "seven leaps in nineteen years"? The average lunar month is 29.5306 days, and there are 12.368 lunar months in a tropical year. The progressive scores of the fractional part of 0.368 are 1/2, 1/3, 3/8, 4/1,7/68. Because 19 tropical year = 6939. 18 days, and 19 lunar year (after seven leap months) * * has 235 moons, which is equal to 6939.438+00 days, so the two are almost the same.
Seven leap months are inserted for nineteen years, and the insertion method is exquisite. The position of the lunar leap month is completely artificial from ancient times to the present, and the position of the leap month has been different in all previous dynasties. Before the Qin Dynasty, the leap month was placed at the end of a year and was called "March". The leap month in the early Han dynasty was placed after September, which was called "post-September". In the first year of Emperor Wu of the Han Dynasty, leap months were inserted in every month of the year. Later, it was stipulated that "the month without neutral gas was the leap month of the previous month", which is still in use today.
Why are there no gas in some months? The average interval between solar terms and solar terms, or neutral gas and neutral gas is 30.4368 days (that is, 65.2422 days in a tropical year is divided into 12 days), while the average interval in a lunar month is 29.5306 days, so the date of solar terms or neutral gas in the lunar month is postponed month by month. At a certain time, the neutral gas is not in the middle of the month, but moves to the end of the month, and the next neutral gas moves to the beginning of the next month.
As mentioned above, when the ancients compiled the lunar calendar, they took twelve China Qi as the symbol of twelve months, that is, the rain was the symbol of the first month, the vernal equinox was the symbol of February, and Grain Rain was the symbol of March ... The month without China Qi was regarded as a leap month, which made the calendar name correspond to China Qi one by one, thus maintaining the original symbol of China Qi.
From the seventh leap of 19, the tropic year of 19 has 228 solar terms and 228 neutral qi, while the lunar calendar 19 has 235 new months. Obviously, there are seven months without solar terms and seven months without neutral atmosphere, so it is logical to designate the months without neutral atmosphere as leap months.
The size of the lunar month is very irregular, sometimes two, three, four big months or two three small months are connected together, and the length of the calendar year varies greatly. The distribution dates of solar terms and gas in the lunar calendar are very unstable and vary greatly. In this way, the lunar calendar seems very complicated. In fact, the lunar calendar still has a certain cyclical law: because the number of days in the 19 tropic year is almost equal to that in the 19 lunar year, every 19 lunar year is almost the same. Every nineteen years, the Gregorian calendar days on the first day of each month in the same month of the lunar calendar are generally the same or one or two days apart. Every nineteen years, solar terms and neutral dates generally repeat, with individual differences of one or two days. The months separated by 19 leap month are repeated or differ by one month.
Stem-branch discipline
Literally speaking, trunks and branches are equivalent to trunks and branches. In ancient China, the sky was dominant and the earth was subordinate. The connection between heaven and stem is called heavenly stem, and the connection between earth and stem is called earthly branch. Together, it is called heavenly stems and earthly branches, or "dry branch" for short.
There are ten heavenly stems, namely A, B, C, D, E, Ji, G, Xin, Ren and Gui, and twelve earthly branches, namely Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai. The ancients paired them in a certain order, without repetition, from Jiazi to Guihai * * * 60 pairs, called Sixty Jiazi.
The ancient Chinese used these 60 pairs of branches to represent the serial numbers of years, months, days and hours, and this is the discipline of branches and branches.
Legend has it that the ministers of the Yellow Emperor era greatly praised the affection of the five elements for the construction of the year, so Party A and Party B named the day, which was called dry; Making a fool of yourself is called a day, and it's called a branch. Branches and branches match to become sixty years old. " This is just a legend. Who founded the main branch in the first place has not been confirmed. However, there are hieroglyphics representing the branches in Oracle Bone Inscriptions unearthed in Yin Ruins, which shows that the discipline of the branches has been used as early as the Yin Dynasty.