Why won’t New Year’s Eve be “New Year’s Eve” in the next five years?

　　◎Beijing Science Center

　　Imagine that in the next five years, every time it is "New Year's Eve, make dumplings", I look at the lunar calendar and find that it is the 29th day of the twelfth lunar month. The Year of the Dragon in 2024 is called the "year without spring" because there is no sign of the beginning of spring. This situation makes people wonder: Is the lunar calendar accurate? There will be no New Year's Eve in the next five years and there will be no Beginning of Spring in the Year of the Dragon in 2024. Is this a coincidence or a rule?

　　There are some irregularities in the lunar calendar

　　The lunar calendar is a traditional lunar calendar system based on the changing phases of the moon, and is usually used to determine lunar festivals and traditional festivals.

　　However, the lunar calendar is not completely accurate as it determines dates based on the phases of the moon and the orbit of the sun, so there will be some differences from the solar calendar (i.e. the Gregorian calendar). In order to adjust the relationship between the lunar calendar and the seasons, the lunar calendar system introduced the concepts of leap years and leap months.

　　A year with a leap month in the lunar calendar is called a leap year. A leap year in the solar calendar means February 29. A leap month in the lunar calendar means adding one month after a certain month. The added month is to adjust the moon phase or the relationship between the month and the month. The relationship between seasons is also used to maintain the correspondence between the lunar year and the solar year.

　　However, even with these adjustments, there may still be some irregularities in the lunar calendar, resulting in unexpected dates in certain circumstances. This irregularity has drawn attention to calendar systems and prompted a deeper understanding of how different calendar systems work. The following introduces you to the three mainstream calendars - lunar calendar, solar calendar, and lunisolar calendar.

　　The lunar calendar, the solar calendar, and the lunisolar calendar are

　　different calendar systems

　　The lunar calendar, the solar calendar and the lunisolar calendar are different calendar systems. They are closely related to the rotation and revolution of the sun, the rotation and revolution of the moon, and the relationship between the two. They reflect human beings' different understanding and utilization of time. These calendar systems have great significance in different cultural and historical contexts.

　　The lunar calendar first appeared, and its origins can be traced back to ancient civilizations. The lunar calendar is related to the "moon". The beginning of a month is the new moon, the middle is the full moon, and then becomes the new moon again. This process usually lasts for 29 or 30 days, which is the total number of days in the month. A year is made up of 12 or 13 months, and the lunar calendar is widely used in many traditional cultures.

　　The Gregorian calendar - also known as the Gregorian calendar, is currently used by most countries around the world. It is related to the "sun" and is a calendar system based on the earth's revolution period around the sun.

　　The period of the earth's revolution around the sun is 365 days, 6 hours, 9 minutes, 9.5 seconds or 365.2564 days, so the length of a year in the solar calendar is set as 365 days, and a year is divided into 12 months. The number of days in each month is not fixed.

　　The twenty-four solar terms are a way of dividing time in ancient China, used to guide farming, farmers' production activities and predict weather changes. People always misunderstand that it is based on the lunar calendar. In fact, it is based on the position of the sun on the ecliptic and the earth. It is determined by revolution, which means it is based on the solar calendar.

　　The lunar calendar is a typical representative of the lunar calendar

　　The Gregorian calendar is a common daily calendar system in modern society and is widely used in business, government, and international communication. But, you know what? There is also a calendar called the lunisolar calendar - the lunar calendar is a typical representative of the lunisolar calendar.

　　The months in the lunar calendar start with the new moon and end with the synodic moon. It originated from "Xia Xiaozheng" narrated by Confucius. This is a unique set of rules based on the Central Plains region and by observing the changing relationship between monsoons and phenology. A calendar that guides agricultural activities.

　　It not only includes the characteristics of the lunar calendar in determining dates based on the phases of the moon, but also takes into account the laws of the sun's movement. It plays an important role in traditional Chinese culture and affects people's lives and festival arrangements. Although modern society has generally adopted the solar calendar, the lunar calendar still maintains an important position in some traditional festivals and customs.

　　For example, when we wonder, "Why will New Year's Eve in the next five years not fall on New Year's Eve?" we need to find the answer from the lunisolar calendar. Because "Shuo Day is the first lunar day of the lunar month", that is to say, the first day of each lunar month is Shuo Day.

　　From "Suo" to "Wang" and then to the next "Suo", the average cycle is 29.5306 days, so the calculated number of days in the lunar month is either 29 days in the small month or 30 days in the big month. If the twelfth lunar month of that year coincides with the small moon and has only 29 days, there will be no New Year's Eve.

　　Similarly, "Why does the Beginning of Spring appear before the Spring Festival?" It is also because the calendars to which these two nodes belong are different. The Beginning of Spring is a solar term, while the Spring Festival is a festival in the lunar calendar. Due to the inconsistent cycles of the two, there is a gap between the solar calendar and the lunar calendar. time dislocation between. Therefore, in some special years, the phenomenon of "no spring years" will occur.

　　lunar calendar, solar calendar, lunar calendar

　　How to use it correctly?

　　The twenty-four solar terms are the most distinctive representatives of the solar calendar. It divides the year into twenty-four solar terms, each of which is about 15 days apart. These solar terms are of great significance in traditional Chinese culture. They are not only used to arrange agricultural activities, but are also closely related to food, clothing, festivals, etc. In some places, people will arrange some customs according to the lunar calendar, such as moving, building houses, etc.; the dates of some sacrificial activities such as worshiping ancestors and gods are also determined according to the lunar calendar; Day banquets, etc. will also be arranged according to the lunar calendar.

　　Perhaps, we cannot simply judge the lunar calendar as "accurate" or "inaccurate", because it carries human beings' perception of nature, life and the universe, and is the inheritance and expression of a culture. It carries people's emotions and memories, connects people's lives and history, and should be respected and cherished by us.

　　(The article originates from the WeChat public account Digital Beijing Science Center)