How is the Beginning of Autumn calculated? Mathematical Calculations in the 24 Solar Terms

How is the Beginning of Autumn calculated? Mathematical Calculations in the 24 Solar Terms
"Li" indicates the beginning of each season of the year. The four "Li" of spring, summer, autumn and winter indicate the beginning of the four solar terms. So, how is the Beginning of Autumn calculated? What are the mathematical calculations in the 24 solar terms? In hot and humid weather, people will become irritable and irritable, so the sixth month of the lunar calendar is also known as "Fanshu" and "Sultryshu". If you want to know whether the sixth lunar month of 2021 is good or not, just check out Mr. Shui Mo's website.

How is the Beginning of Autumn calculated?

Formula: [Y*D+C]-L
Beginning of Autumn: Y=last two digits of the year, D=0.2422, L=leap year number, in the 21st century C=7.5, in the 20th century C=8.35.
For example: The date of the beginning of autumn in 2088 = [88×0.2422+7.5]-[88/4]=28-22=6, so August 6 is the beginning of autumn.
Exception: For 2002, add 1 day to the result.

What are the mathematical calculations in the 24 solar terms?

The calculation formula for the 24 solar terms is: [Y×D+C]-L
Formula interpretation: Y=the last two digits of the year, D=0.2422, L=the number of leap years, that is, the last two digits of the year multiplied by 0.2422 plus the integer value of C minus the number of leap years.
Note: The C value for each solar term is different.

Why are the dates of the solar terms different every year?

This is related to the calendar made by people.
The current solar calendar (Gregorian calendar) has either 365 or 366 days in a year, which is different from the tropical year of 365.2422 days.
Therefore, the time of the solar terms changes every year, but the difference between each solar term is only one or two days at most.
If we use the Heavenly Stems and Earthly Branches system and assume that there are 360 ​​days in a year, each solar term will have a fixed Heavenly Stems and Earthly Branches, called a Fu Tou.
But in fact, the duration of a tropical year is 365.2422 days, which leads to the situation that the symbol head does not match the solar terms.

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