Solar term astronomical phenomena

In ancient China, the longest shadow of the sun was defined as "solstice" (also known as long solstice, long solstice and winter solstice), and the shortest shadow was defined as "short solstice" (also known as short solstice and summer solstice). When the length of day and night in summer is equal, it is defined as "vernal equinox" and "autumn equinox". There were only four solar terms in Shang Dynasty and eight solar terms in Zhou Dynasty. Twenty-four solar terms were completely established in Qin and Han Dynasties.

In BC 104, taichu calendar written by Deng officially defined the 24 solar terms in the calendar and determined their astronomical positions. Deng Ping was born in the early Han Dynasty. He was an official during the reign of Emperor Wu of the Han Dynasty. Many people don't know why there are lunar and solar calendars. They only know that China uses the lunar calendar and the west uses the Gregorian calendar. The lunar calendar is defined according to the phase of the moon, that is, the orbit of the moon around the earth is one month, and then 12 months (leap year 13) is spelled into one year. The lunar calendar is characterized by the moon, so there are 15 full moons. On the contrary, years are meaningless (not culture), but a collection of months. The Gregorian calendar is defined according to the seasons, that is, the earth revolves around the sun for one year, and then the year is divided into about 12 parts, each part is called a month.

The Gregorian calendar is characterized by the meaning of years, so the seasons in each period are similar. On the contrary, the month is meaningless, just the average of one year. Twenty-four solar terms are a traditional calendar phenomenon of the unity of astronomy and humanities in China, which has a history of thousands of years. Twenty-four solar terms are a cultural time scale formed by the combination of traditional astronomical calendar, natural phenology and social life in China. Solar terms are the key to climate change. From the distant celestial bodies to the nearby life and labor, every solar term is people's perception of nature and understanding of life. Generally speaking, there were 24 solar terms in Xia and Shang Dynasties. The first solar terms are vernal equinox and autumnal equinox, winter is the solstice, and summer is the solstice. From the Western Zhou Dynasty to the Spring and Autumn Period, eight solar terms (including beginning of spring, long summer, beginning of autumn and beginning of winter) were formed at four o'clock, and finally, from the Warring States Period to the Western Han Dynasty, they became twenty-four solar terms similar to the current version. 165438+1October 30th, 24 solar terms in China were officially listed in UNESCO's Representative List of Intangible Cultural Heritage of Humanity. As early as the Eastern Zhou Dynasty, the Spring and Autumn Period and the Warring States Period, the working people of the Han nationality had the concept of "North and South to Japan". Then, people use the natural phenomena such as the relationship between the sun and the moon, the weather and the growth of animals and plants at the beginning and middle of the month to divide the year into 24 equal parts. And gave each division a proper noun, that is, twenty-four solar terms.