How to calculate the lunar calendar for leap months in 2023
2023 is In February, its lunar year has a total of 384 days, and the Gregorian year is an ordinary year, with a total of 365 days.Leap month is a special calendar term, because there is an error in the calculation of the time of the lunar year and the time of the return year, so it is necessary to make up for the error by setting the leap month.
What is the meaning of leap month
The lunar calendar is a traditional calendar in my country.The solar calendar is based on the earth’s revolution around the sun as a tropical year.The lunar calendar is based on the changes of the moon’s yin, yang, and yin, and the date and month are determined according to the phase of the moon.A lunar lunar lunar month is 29.5306 days on average, and 12 lunar lunar months are 354 or 355 days, which is about 11 days away from a solar lunar year (about 365.25 days), and the cumulative time gap over 3 years will exceed one month.Because of the addition of the solar calendar, the lunar calendar is a calendar that takes into account the relationship between the sun, the moon and the earth, and is a yin-yang calendar.
Because the pure lunar calendar does not consider the movement of the earth around the sun, the changes of the four seasons have no fixed time on the lunar calendar and cannot reflect the seasons.Unlike the Gregorian calendar year, which is fixed at 365 days or 366 days, the number of days between the lunar calendar year and the solar calendar year sometimes differs by one month.Adjustments are made to match the total number of days in the two years.Leap month is a way of setting the leap month in the calendar.
The year 2023 is a leap month
AD 2023, the Gregorian calendar year, has a total of 365 days and 53 weeks.The lunar calendar is the year of the Guimao (the Year of the Rabbit), with the leap second month, a total of 384 days.Due to the leap February in 2023, there are two beginning springs in the lunar year of 2023, so this year is called the Double Spring Year.There are two Februarys in one year of the lunar calendar, and the second February is the leap February.The Spring Festival and the Dragon Head Festival are the earliest, and the last year of the Shangsi Festival is usually in February.The frequency of Leap February is second only to Leap March, with a moderate frequency around the 21st century, generally occurring once every 19 years (such as 2004 and 2023).Since then, the frequency of leap February has gradually decreased and it has become a rare leap month, which occurs once every century in the 25th and 28th centuries.
Calculation method of leap month
The middle month of the lunar year is based on the length of the synodic month of 29.5306 days, so the big month is 30 days and the small month is 29 days.In order to ensure that the first day of each month (the first day of the new year) must be the new day, the arrangement of the big and small months is not fixed, but it needs to be determined through strict observation and calculation.Therefore, it is common for two consecutive months in the lunar calendar to be the big month or the small month, and even in 1990, March and April were small months, and September, October, winter, and twelfth months were four consecutive months.Rare exception of the month.
How long does it take to add a leap month? The best way is to find the least common multiple of the number of days in a tropical year and the number of days in a synodic month:we hope that the number of days in m tropical years is equal to the number of days in n lunar months, that is, there should be an equation:
m × 365.2422=n × 29.5306.
In this equation, we cannot find m and n directly, but we can find their ratio:M/N=29.5306/365.2422
It is approximated by:3/7 5/62 8/99
In these fractions, the numerator represents the number of tropical years and the denominator represents the number of synodic months.For example, the sixth fractional formula = means that 7 leap months must be added to the 19 tropical years.
Comparison of the results of adding 7 leap months in 19 tropical years:
19 tropical years = 365.2422 days × 19 = 6939.6018 days,
235 synodic months = 354.3672 days × 12 + 383.879 days × 7 = 6939.691 days.
After adding 7 leap months to the 19 tropical years, the contradiction is eliminated only slightly:6939.6910 - 6939.6018 = 0.0892 (days)—that is, more than 2 hours and 8 minutes, which is accurate enough.
The lunar calendar adopts the method of 19 years plus 7 leap months, that is, the "Nineteen Years Seven Intercalary Method", which well coordinates the return year and the lunar year, so that the New Year’s Day (Spring Festival) of the lunar calendar is always the same.Keep in late winter and early spring.The ancients called the 235 lunar months "intercalary weeks".
The method of setting intercalary in the lunar calendar can make the average length of the lunar year close to the tropical year, and the months in the lunar calendar have distinct moon phase characteristics, maintaining the characteristics of the best of both worlds in the solar and lunar calendars.
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