Are the 24 solar terms calculated according to the lunar calendar or the solar calendar?

The 24 solar terms are calculated according to the lunar calendar.

Lunar calendar is a calendar handed down from ancient China to guide agricultural production, so it is called lunar calendar. In the lunar calendar based on the ancient lunar calendar, some signs convenient for agricultural production have been added, including some knowledge of the solar calendar, such as the 24 solar terms in the elephant trunk calendar, so it is a combined calendar of yin and yang.

Twenty-four solar terms are special festivals in the dry calendar, indicating the change of natural rhythm and establishing "December construction". At first, it was based on the changing stars. The Big Dipper rotates in cycles, and bucket handle rotates around the east, south, west and north in cycles, which is called one of the "years old". Each rotation cycle begins in beginning of spring and ends in severe cold.

Introduction of solar calendar

Lunar calendar refers to the calendar arranged according to the moon phase cycle, with the moon circling the earth as January. In China, the moon is also called "lunar", so the calendar with the moon as the reference is called lunar calendar. The moon in the lunar calendar is called the new moon. Gregorian calendar, as its name implies, is a common calendar in most countries in the world. It originated from a calendar approved by Pope Gregory XIII in 1582 and is one of the solar calendars.

The solar calendar defines a year based on the movement period of the earth's revolution and the orbit of the earth around the sun. China didn't find the knowledge that Heliocentrism and the earth revolve around the sun in ancient times, so it took the relative movement of the sun as the research object, so it was called the solar calendar.