Which dynasty officially set 24 solar terms in the calendar?
In BC 104, the taichu calendar written by Deng Ping officially set 24 solar terms in the calendar, and defined the astronomical position of the 24 solar terms. Twenty-four solar terms refer to the 24 special festivals in the dry calendar (or lunar calendar) that indicate seasonal changes, which were originally determined by the direction of the top of the bucket handle of the Big Dipper.
In the Western Han Dynasty, the names of the twenty-four solar terms first appeared in the document "Tian Zi Xun in Huainan". During the period of Emperor Wu of the Han Dynasty, the twenty-four solar terms were absorbed into the taichu calendar Law as a supplement to the calendar guiding agriculture.
The average time method was used to divide solar terms for a long time in the Han Dynasty and its later period. The method of "leveling the sky" is to determine the shortest winter solstice by photogrammetry, divide the date between the winter solstice and the next winter solstice into twelve equal parts, which is called "Zhongqi", and then divide the dates between adjacent Zhongqi into equal parts, which is called "solar terms".
On average, there is a "neutral gas" and a "solar term" every month, which are collectively called "24 solar terms". "leveling method" is a time average method, and the interval of each solar term is about 15 days. The uneven motion of the sun on the ecliptic is not considered in the calculation. Using the method of "balancing qi" to divide the solar terms starts from the solstice of winter and ends with heavy snow.
Extended data:
The naming of the twenty-four solar terms reflects three seasons, phenology and climate changes. The solar terms reflecting the changes of the four seasons are: beginning of spring, Spring Equinox, Long Summer, Summer Solstice, beginning of autumn, Autumn Equinox, beginning of winter and Winter Solstice. Among them, beginning of spring, Changxia, beginning of autumn and beginning of winter are collectively called "Sili", which means the beginning of the four seasons.
There are five solar terms reflecting temperature changes: slight summer heat, great summer heat, summer heat, slight cold and severe cold. There are seven solar terms reflecting weather phenomena: rain, Grain Rain, white dew, cold dew, first frost, light snow and heavy snow. There are four solar terms reflecting phenological phenomena: Jing Zhe, Qing Ming, Xiaoman and Mang Zi.
Beginning of spring is divided from astronomy, but in nature and people's minds, spring is warm and flowers are fragrant. Spring is growth, cultivation and sowing. It has been thousands of years since beginning of spring ushered in spring.
The dividing line between winter and spring in beginning of spring and China (when the average temperature reaches 65,438+00 degrees Celsius for five consecutive days, it is regarded as spring), from Guilin, Guangxi to Ganzhou, Jiangxi. In the area south of this line, beginning of spring sometimes smells of spring, but 93% of the land in China is still winter, while in Heilongjiang, spring usually comes in Grain Rain during the long summer.
Speaking of beginning of spring, people obviously feel that the days are getting longer and the sun is getting warmer. Temperature, sunshine and rainfall are often at the turning point of the year and tend to rise or increase. The growth of crops in early spring is accelerated, and the water consumption for bolting rape and jointing wheat is increased. Irrigation and topdressing should be done in time to promote growth.
Baidu encyclopedia-24 solar terms