How many solar terms are there in a year, and how many days are there in each solar term?

A year is divided into 24 solar terms, and each solar term has fifteen days. The ancients in China divided the sun's annual trajectory into 24 equal parts, each of which was divided into a solar term, and each solar term had three cycles, each of which was 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 twenty-four solar terms reflect the influence of the sun on the earth and belong to the solar calendar category. It is a knowledge system formed by observing the movement of the sun in a year and understanding the changing laws of the four seasons, climate and phenology in a year. It not only plays a guiding role in agricultural production, but also affects the food, clothing, housing and transportation of ancient people, and even cultural concepts. The current lunar calendar absorbs the solar terms of the trunk calendar as a supplement to the calendar, and is adjusted to conform to the tropic year through the leap method, forming a combined calendar of yin and yang.