Xinhua News Agency, Nanjing, January 22 (Reporters Wang Jueying and Qiu Bingqing) Today is the traditional festival of Spring Festival. The attentive public may find that this year's Spring Festival comes earlier than the previous two years.
Why is the Spring Festival date early and late?
According to astronomy science experts, this is related to the calculation rules of the Chinese lunar calendar.
Simply put, if there was no leap month in the previous lunar year, the Spring Festival will come earlier.
According to Wang Kechao, director of science popularization at the Purple Mountain Observatory of the Chinese Academy of Sciences, the Spring Festival is the first day of the first lunar month in my country, but its date in the Gregorian calendar is not fixed, and generally fluctuates between late January and late February in the Gregorian calendar.
The Gregorian calendar has 365 days in an ordinary year and 366 days in a leap year.
The lunar calendar is based on the cycle of the waxing and waning of the moon and the length of the return year. A synodic month has an average of about 29.5 days, and an average lunar year has 354 or 355 days, which is about 11 days less than the Gregorian calendar year on average.
If this time difference continues for a long time, the Spring Festival will be in summer. Therefore, the method of setting a leap month in the lunar calendar is used to make the month correspond to the season.
The arrangement of the leap month is related to the solar terms.
Wang Kechao said that in the lunar calendar year, the first synodic month after the winter solstice with no energy is determined as a leap month.
Zhongqi refers to the even-numbered 12 solar terms in the twenty-four solar terms starting from the beginning of spring.
On average, there are 12 normal years and 7 leap years in every 19 lunar years, so there is a saying of "seven leap years in nineteen years".
A lunar leap year has 383 or 384 days, about 19 days more than a Gregorian year on average.
After intercalation, the total number of days in every 19 Gregorian calendar and lunar calendar years is basically the same.
"If there was no leap month in the previous lunar year, the Spring Festival will be about 11 days earlier than the previous year. If there was a leap month in the previous lunar year, the Spring Festival will be delayed by about 19 days." Wang Kechao said that the Spring Festival will be on the Gregorian calendar. Fluctuates between late April and late February.
For example, during the 75 years from 1949 to 2023, the earliest Spring Festival occurred on January 21, which was the Spring Festival in 1966, while the latest Spring Festival appeared on February 20, which was the Spring Festival in 1985.
Poster Production: Xu Zhan