Are the 24 solar terms determined by the lunar calendar or the solar calendar?

As early as the Spring and Autumn Period and the Warring States Period, the Chinese people had the concept of Solstice in the South and Solstice in the North. Subsequently, people divided the year into 24 equal parts according to the relationship between the running position of the sun and the moon at the beginning of the month and natural phenomena such as weather, animal and plant growth, and gave each equal part a proper term, which is the 24 solar terms. By the end of the Warring States Period, solar terms had eight names, including beginning of spring, Equinox, Long Summer, Summer Solstice, beginning of autumn, Equinox, beginning of winter and Winter Solstice. These eight solar terms are the most important of the 24 solar terms. These eight solar terms indicate the change of seasons and clearly divide the four seasons of the year. Later, when the book Huai Nan Zi was published, the names of the 24 solar terms were exactly the same as those of the modern ones.

In fact, the 24 solar terms are defined according to the solar calendar. That is, according to the position of the sun on the ecliptic, a year is divided into 24 equal parts. That is to say, the ecliptic is divided into 24 equal parts, each equal part accounts for 15 degrees of the ecliptic. Because the time required for the sun to pass through each bisection is almost equal, the Gregorian calendar dates of the 24 solar terms are roughly the same: the first half of the year is around 6 and 2 1, and the second half is around 8 and 23.