How to switch time between the lunar calendar and the solar calendar?

The first day of each month is called the new moon, and the last day is called darkness. The fifteenth, sixteenth or seventeenth day of the lunar calendar is called Wangwang, and the day after Wangwang is called Wangwang, so every year's Lunar New Year's Eve is not on the same day. The basis of the lunar calendar is the tropic of Capricorn and the first moon. The tropic year is the time required for the sun to pass through vernal equinox twice in a row, that is, 365.2422 days (365 days, 5 hours, 48 minutes and 46 seconds). "The first month of the lunar calendar" is the time between two consecutive new moons (new moons) or two full moons (full moons), that is, 29.5306 days (June 29th 12 hours, 44 minutes and 3 seconds).

Because 12 "Wang Shuo Moon" is only 354.3672 days, which is more than 10 days different from 365.2422 days in the tropic year, this difference accumulates and becomes a leap month. As early as the Spring and Autumn Period in 5600 BC, China calendar adopted the arrangement of seven leap months in 19 years.

However, the calculation method of the lunar calendar in China is different from that in Tibet and South Korea, and there is generally a difference of one or two days.

The date of the lunar calendar is based on the full moon, which takes each new moon as the first day, and the full moon is the fifteenth day (the 16th day of the big month) and the 29th day (the 30th day of the big month). However, at present, the date of the solar calendar is usually used to express the time. If you want to convert the date of the solar calendar into the date of the lunar calendar, you can use the following two methods: one is to view the newly edited perpetual calendar, for example, what day is June 8 of the lunar calendar 1984? Turning to the perpetual calendar, June 10 is the first day of November in the lunar calendar, so it is inferred that June 8 is the ninth day of September in the lunar calendar. Secondly, we can use the following formula to calculate the lunar calendar date:

Suppose: the number of AD years-1977 (or1901) = 4q+r.

Then: Lunar date =14q+10.6 (r+1)+the day of the year-29.5n.

(Note: In the formula, Q, R and N are all natural numbers, R.

Example:1The lunar calendar date of May 7, 994 is:

1994- 1977= 17=4×4+ 1

Therefore, q = 4, r = 1, so the date of the seventh day of the fifth lunar month is:

14×4+ 10.6（ 1+ 1）+（3 1+28+3 1+30+7）-29.5n

= 204.2-29.5 Newton

Then divide 204.2 by 29.5 to get the quotient 6...27.2, where 6 is the value of n and the remainder 27 is the 27th day of the lunar calendar.