How did Liu Ren Jr. calculate when he met a leap month?

When Liu Ren Jr. meets a leap moon, there are three algorithms: determining the day sequence by the phase of the moon, and determining the month sequence by neutral gas.

1, set the date order according to the moon phase.

It calculates the date and time of the conjunction of the sun and the moon one by one, and the first day of each month is the date of the conjunction; Determine the size of last month according to the number of days included in the second conjunction. If the interval between this new moon and the next one is 30 days, then this month is the big moon; If it is only once every 29 days, it is an abortion.

2. Set the month order with neutral gas.

First of all, it is known that a tropic year has 12 neutral phases, but it contains 365.2422 ÷ 29.5306 = 2.3682 moons. After several cycles of calendar month, there must be a calendar month without neutral phase. "Han Shu Li Biao" contains: "If the new moon fails to count, it is called leap moon". This month without neutrality is a leap month. When the previous calendar day is a few months, it is a leap month.

Introduction to the birth of leap month;

Leap moon refers to a phenomenon in the lunar calendar. The lunar calendar arranges the big moon and the small moon, that is, the moon, according to the moon's roundness and wane. The length of a moon is 29.5306 days, which is the cycle of the moon's profit and loss. According to the lunar calendar, there are 30 days for the big moon and 29 days for the small moon, and a year is 12 months ***354 days. Lunar months have no seasonal significance.

In this way, 12 moons constitute the Han calendar year, with a length of 354.3672 days, which is 10.88 days less than 365.2422 days in the tropic year, that is, 0.9 1 day less every month, so the difference of one year is1/kloc-0.

In this way, it is naturally impossible to meet the needs of agricultural production. In order to overcome this problem, ancestors found a way to fly over the moon on the basis of astronomical observation.