We are familiar with solar terms and songs. Why did the ancients divide a year into so many solar terms?

Twenty-four solar terms are the product of our ancestors' long-term production practice, which summarizes the relationship between astronomy, meteorology and agriculture, reflects the changes of seasons, cold and heat, and weather, and is the crystallization of the wisdom of our working people.

The earth goes around the sun once a year (365 days, 5:48:46)- weeks. From the earth, we see the sun moving in the sky once a year, and the route of this movement is called the ecliptic. The position of the sun on the ecliptic is measured by the ecliptic.

At the vernal equinox and autumnal equinox, the ecliptic intersects the equatorial plane. At this time, the ecliptic is 0 degrees and 180 degrees respectively, and the sun shines directly on the equator, and day and night are equal.

On the summer solstice, the direct sunlight is 23.5 degrees north latitude and 90 degrees yellow longitude, which is the longest day in the northern hemisphere.

On the solstice in winter, the direct sunlight is 23.5 degrees south latitude and 270 degrees yellow longitude, and the daytime in the northern hemisphere is the shortest.

The vernal equinox and autumnal equinox are in the middle of spring and autumn, and the summer solstice and winter solstice are in the middle of summer and winter. In this way, a year can be divided into four sections: vernal equinox, summer solstice, autumn equinox and winter solstice. If each segment is divided into six segments, the sun runs 15 degrees on the ecliptic, and each segment is about 15 days, which can be divided into 24 segments throughout the year. According to the lunar calendar, the sun is a solar term every 15 degrees from 0 degrees on the ecliptic, and it is * all year round.

? From the earth observation, the orbit of the sun between stars or celestial spheres in a year is called the ecliptic, which is bounded by the 360-degree meridian. The twenty-four solar terms just divide the ecliptic into fourteen equal parts, that is, the difference between the qi is 15 degrees. At the vernal equinox, the longitude of the Yellow River is 0 degrees, at Tomb-Sweeping Day time, it is 15 degrees, and so on.