How long does each solar term last? How did the solar terms come from?

1 and 24 solar terms have fifteen days each.

2. The ancient people in China divided the sun's annual trajectory into 24 equal parts, each equal part is a solar term, and each solar term has three cycles, and each cycle is five days. According to the law of the operation of heaven and earth, the ancients determined the starting point and ending point of the four-season cycle and divided the 24 solar terms. The trajectory of the sun in a year is divided into 24 equal parts, each of which is a "solar term", collectively called "twenty-four solar terms".

Because it takes 365 days for the earth to go around the sun, there is a solar term every fifteen days, and each solar term represents different changes in climate, phenology and time.