Why do you dance every four years?

Four years later, the remaining small part, exactly 24 hours, is an extra day.

Leap year refers to the year with leap day in Gregorian calendar or summer calendar, and the year with leap month in China lunar calendar. The period of the earth's orbit around the sun is 365 days, 5 hours, 48 minutes and 46 seconds (365.438+09 days), which is the tropic of cancer. The Gregorian calendar has an average of only 365 days a year, which is about 0.2422 days shorter than the tropical year. The remaining time is about one day in four years, plus February of the fourth year, making the calendar year of that year 366 days, and this year is a leap year. The current Gregorian calendar has 97 leap years every 400 years. The average summer calendar is only 354 days a year, which is 0.367 1 day shorter than the 12 months of the lunar calendar. In order to make the first day of each month coincide with the new moon, it is stipulated that the end of 1 1 year will increase by 1 day every 30 years. This calendar year has 355 days, which is a leap year. As a kind of China lunar calendar, the number of days in each month depends on the monthly deficit, and the time of one year is based on 12 months, and the normal year is about 1 1 day less than a tropical year. In order to close the earth's orbit around the sun, that is, the tropic year, one month is added every two to four years, and the added month is a leap month. The year with leap month is 13 months, and the calendar year is 384 or 385 days. This year is also called leap year.

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.

Interviewee: Inter Milan Wang-the first generation master149-1912: 43.