Why are the 24 solar terms recorded according to the Gregorian calendar? For example, Tomb-Sweeping Day is a day on April 456 every year. Isn't there a Gregorian calendar in ancient times?

The current 24 solar terms are only calculated by the Gregorian calendar for the convenience of modern people, so the start and end dates of the same solar term are not the same in different years.

In ancient times, it was calculated according to the lunar calendar. Every month in the lunar calendar is thirty days, including two solar terms, and each solar term has fifteen days ~ ~ ~

The 24 solar terms, namely beginning of spring, Rain, Surprise, Spring Equinox, Qingming, Grain Rain, Changxia, Xiaoman, Mangzhong, Summer Solstice, Slight Summer, Great Summer, beginning of autumn, Early Summer, Millennium, Autumn Equinox, Cold Dew, Early Frost, beginning of winter, Light Snow, Winter Solstice, Slight Cold and Severe Cold, are all based on the sun's ecliptic.

When I was a child, I heard from my grandmother. That's about it ~ ~ ~