What is a leap month and when does it appear?

In leap months, the lunar calendar is based on the moon's orbit around the earth. Every year, there is a difference of about 10/between 5: 48: 46 and1on the 365th of the tropic of Capricorn, so we have to leap for one month every three years, two months every five years and seven months every nineteen years. In this way, every additional month in a leap year is called a leap month. Leap month is added after a certain month. It's called leap moon.

Leap month and leap year

In order to adjust the average length of calendar year to match the length of tropical year, it is sometimes necessary to adjust the length of individual months or increase the number of months in a year. This adjusted month or added month is called "leap month".

The leap month calendar was first invented and used in China. It started around 500 BC, which was 160 years earlier than ancient Greece. The calendar of our country adopts the method of seven leap months in nineteen years, which is different in different periods and countries.

In the traditional Chinese lunar calendar, when the length of the first lunar month (29.5306) is the average of 1 month, that is, 12 months in a year and the length of the tropical year (365.2422) is about 10 and 2 1 day, it is necessary to set a leap. In the six-year calendar in ancient China, the leap month method was adopted, with three years 1 month, five years and two months, and 19 years and seven months. Every month in a leap year is called "leap month". The leap month is placed at the end of the year. For example, the seal script used in the early years of the Qin Dynasty and the Western Han Dynasty started in October and ended in September. Leap month is placed after September, which is called "post-September". When the taichu calendar Law was enacted in the early years of the Western Han Dynasty, leap months were inserted in every month of the year, and it was stipulated that lifeless months were regarded as leap months, and the month sequence was still the month sequence of last month, so long as it was called "leap months". This leap rule is the most reasonable in a smooth calendar. In the Qing dynasty, the constitution continued, and it was changed into a fixed-atmosphere calendar. If we continue to simply follow the rule that there is no central leap, it is possible to set up two leap months a year. Therefore, the leap year is defined as 13 months between two winter solstices, and the first month of a leap year is defined as leap month. This rule has been in use ever since. In leap years, April, May and June are the most frequent, and September, 1 October are the least. 1 1 month,1February,1month will not appear, at least for several thousand years.

In the Gregorian calendar, leap month is not a year plus a month, but a month plus a day to ensure that the Gregorian calendar year is consistent with the tropic year. For example, julian calendar and the current Gregorian calendar generally have 365 days a year. Usually every four years (the current Gregorian calendar is sometimes eight years apart), one day is added in February, and this year it is 366 days. February this year is a leap month, and this year is also called a leap year.