Why are the 24 solar terms fixed with the solar calendar?

Gregorian calendar and Gregorian calendar.

1. Gregorian calendar: The Gregorian calendar, that is, the solar calendar, is a calendar based on the movement period of the earth around the sun. The month and date of the solar calendar coincide with the position of the sun on the ecliptic. The twenty-four solar terms in ancient China were supplementary calendars to guide farming, which were divided according to the position of the sun on the ecliptic. The twenty-four solar terms of the lunar calendar belong to the solar calendar, which is consistent with the solar calendar.

2, Gregorian calendar: Gregorian calendar is also a solar calendar, which does not reflect the moon phase, but only reflects the tropical year, so the Gregorian calendar and the 24 solar terms can be well matched.