How to calculate the time minutes of the 24 solar terms?

What we generally know now is that the sun and the earth have been constantly revolving and rotating. The earth's orbit around the sun is usually called the ecliptic, and the 24 solar terms are divided according to the position of the sun on the ecliptic. First of all, when the sun shines directly on the equator, it is designated as "the longitude of the Yellow River is zero", that is, the vernal equinox. From here, every advance of 15 degrees is a solar term, which extends downwards from the vernal equinox, Qingming, Grain Rain, Changxia and so on. After running for a week, it will return to the vernal equinox, which is a 360-degree tropic year, so it is divided into 24 solar terms.

The twenty-four solar terms are actually a "moment", not a "day". During the earth's revolution and rotation, because the earth's rotation axis has an inclination of 23.5 degrees relative to the coaxial axis, the elevation angle of the sun is higher at noon in summer and lower in winter, which affects the temperature and season throughout the year. In order to let our ancestors know about the climate change in cold and summer, decide the progress of farming or serve as a reference for daily life, ancient historians stipulated that the tropical year from winter solstice to winter solstice of the following year should be divided into twelve equal parts, which is called zhongqi; Then, the two equal parts of neutral gas are called solar terms, which are the source of 24 solar terms. The formulation of this solar term is called "flat gas method". However, because the earth's orbit around the sun is elliptical. Near the sun, the speed of the earth's revolution is faster, but far away, it is slower. For the Central Plains region where this calendar was made at that time, some solar terms could not reflect the real climate. Therefore, since the Qing Dynasty, the vernal equinox has been set at 0 degrees, and every time the sun runs 15 degrees on the ecliptic, it is set as a solar term or a solar term. Now solar terms and solar terms are collectively referred to as "solar terms".

Astronomical knowledge is mysterious, and so are our ancestors.