Does every lunar tenth month have 30 days?
No, not every lunar tenth month has 30 days!This is because the lunar calendar strictly determines the length of the month based on astronomical phenomena. At the end of the month, there may be no 30th day, meaning that the month is a small month.
The size of each month in the lunar calendar is not fixed every year. If the number of days between two consecutive new moons is 30 days, then the month has 30 days; if it is 29 days, then it does not have 30 days.
Whether the lunar tenth month has 30 days depends on the actual climate and seasonal conditions of each year, and there is no regular pattern.
How are the large and small months of the lunar calendar divided?
The distinction between large and small months is strictly based on the moon's phases and is not fixed.The size of the lunar months is calculated according to the patterns of solar and lunar eclipses. It is generally considered that odd-numbered months are small and even-numbered months are large. Every thirty years form a leap cycle, adding eleven leap days, and it is stipulated that the leap days are added at the end of the twelfth month in the years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26, and 29, which is called a leap month in the twelfth month.
The current Gregorian calendar's method of adding 97 leap days in 400 years is equivalent to the ancient Chinese traditional calendar's "leap cycle." Specifically, it is added to the years divisible by 4 (except century years), and century years divisible by 400.
When the Western Han Dynasty established the "Taichu Calendar," it was stipulated that the month without a solar term would be a leap month, and this method of inserting leap months was adopted thereafter. At this time, the new leap cycle was a natural result after more precise measurements of the tropical year and the synodic month. Its significance for arranging leap months became less important. From Li Chunfeng's "Lingde Calendar" in the Tang Dynasty, the leap cycle was no longer determined.
