When is the third day?

It refers to the 1 day and 2nd day of every ten days of the lunar calendar, namely 1 day and 2nd day, 1 1 day,12nd day and 2 1 day and 22nd day of the lunar calendar.

According to heavenly stems and earthly branches, "A, B, C, D, E, Ji, G, Xin, Man and Ghost" are called ten days' achievements.

Each month is divided into three parts, 1- 10, 1 1-20, 2 1-30, with a period of ten days, and the tenth day is ten days.

The days from 1- 10,1-20 and 2 1-30 are respectively: A day, B day, C day, D day, E day, Ji day, Geng day, Xin day, Ren day and Deck day.

Extended data:

Heavenly stems and earthly branches, referred to as Ganzhi for short, originated from the observation of astronomical phenomena in ancient China.

According to the method of recording the sun in ancient heavenly stems and earthly branches, the heavenly stems are divided into five elements: A and B belong to wood, A is sunny wood, and B is shady wood; C and D are fire, C is yang fire and D is yin fire; Wuji belongs to the soil, Wuji is the positive soil, Wuji is the negative soil; Belonging to gold, Geng is Jin Yang and Xin is Yin Jin; Both nonyl and decyl belong to water, nonyl is yang water and decyl is yin water.

The 60th day of a year is roughly a 2-month cycle; Reuse after recycling, recycle, recycle. According to the confirmed documents, the chronological date of the main branch began in February of the third year of Lu Yingong ("Food is the sky", which was converted into 51 years on February 22, 720 BC in Zhou Pingwang).

Compared with recording a month and a day, it is very easy to calculate the date interval of historical events and whether there is a leap month. Because the 29th or 30th day of each month in the China calendar (lunar calendar) is uncertain, and whether there is a leap month is unknown, if the date spans several months, it will be very difficult to calculate. As for the correspondence between a certain day and the main branch, you can check the perpetual calendar.

Reference source: Baidu Encyclopedia-heavenly stems and earthly branches

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