How did the 24 solar terms come out? Even used geographical knowledge.

1. The earth revolves around the sun at 5: 48: 46 every 365 days 1 circle, and rotates every 23 hours, 56 minutes and 4 seconds 1 circle. Because the orbital plane of the earth's rotation around the sun is not the same as the equatorial plane, but keeps a certain inclination, so the position of direct sunlight on the earth is different all year round. In the northern hemisphere, when the direct sun is 23.5 north latitude, it is called summer solstice in astronomy; The direct sunlight at 23.5 south latitude is called the winter solstice; The solstice in summer and the solstice in winter mean that they are halfway between summer and winter.

2. When the sun shines directly on the equator twice a year, it is called vernal equinox and autumnal equinox respectively; The vernal equinox and autumnal equinox refer to the middle of spring and autumn; The days of these two days are as long as the nights. In this way, a year can be divided into four parts: vernal equinox, summer solstice, autumn equinox and winter solstice. If each section is divided into six small sections, each small section is about 15 days, and the whole year can be divided into 24 small sections, thus producing 24 solar terms.