Are vernal equinox, summer solstice and autumn solstice calculated according to solar calendar or lunar calendar?

The 24 solar terms are calculated according to the movement of the sun.

Generally speaking, the leveling method is to divide the tropic of cancer into annual averages.

It is different because every month of the lunar calendar is based on the first month of the lunar calendar, and the first day of each year is the first month of the lunar calendar (after the Han Dynasty). Because of epoch and leap, solar terms are used as a measure. Some people think that day in beginning of spring is the first month of the lunar calendar ... but the first and last days of a month are determined by the first month of the lunar calendar. The first day of each month and the first year of the capital are new moons.

However, the twelfth lunar month lasts only about 354 days a year. A leap in three years and a leap in five years (a leap in one month) will keep the total number of days in the lunar year and the tropic year unchanged in a certain year, so as to prevent the deviation of solar phenology and months from affecting farming for more than one month.

Therefore, the position of solar terms in the lunar calendar is not fixed, because there will be about eleven or thirty days less each year.

There are 365 leap days in the Gregorian calendar every year, so the solar terms in the Gregorian calendar are the same ... after all, there is only a quarter of an hour difference every year.

The former method is typical of the earth-expensive method .. There is a picture called Seven Scales and Six Rooms in Weekly Parallel Calculations, which also has the shadow length of 24 solar terms.

But maybe it's because of the model of celestial theory. In a word, from a modern point of view, it is nonsense.

In addition, although Zhu's quotations and other documents mentioned 360-degree Sunday, it still has 365.25 degrees on Sunday.

Generally speaking, most astronomical records or some astronomical calculations start at 365.25 degrees on Sunday, so they need to be converted.

In addition, according to the astronomical training of Huai Nan Zi, Meng Xi's written talk and Hanshu, etc.

I prefer Professor Chen's point of view.

In ancient times, the coordinates of the ecliptic were right ascension degrees.

Because I don't believe in Shen Kuo's slip of the pen or Huainanzi's blind writing ... although Huainanzi blindly wrote many fairy tales.