We often say that there are 365 days in a year, which is based on the internationally accepted Gregorian calendar, which is commonly known as the "Gregorian calendar" in China, and is formulated according to the movement cycle of the earth around the sun, that is, a return year. The length of a return year is 3652422 days, or 365 days, 5 hours, 48 minutes and 46 seconds.
According to the calendar data released by the Purple Mountain Astronomical Observatory of the Chinese Academy of Sciences, 2024 is a leap year in the Gregorian calendar, with 29 days in February, with a total of 366 days in the year, while the upcoming Jiachen year (Year of the Dragon) in the lunar calendar is a normal year, with a total of 354 days in the year. Why is 2024 more days in the Gregorian calendar than the Year of the Dragon in the lunar calendar?
Why is there a difference in age between the Gregorian calendar and the lunar calendar?
Why is there a difference in age between the Gregorian calendar and the lunar calendar?What are the Gregorian and lunar calendars based on?From ancient times to the present, the way people calculate time is closely related to astronomy, and the movement of celestial bodies such as the sun, the earth, and the moon is used as the basis for calculating time. According to experts, the Gregorian calendar and the lunar calendar are two different calendars in astronomy, and the difference between the Gregorian calendar and the lunar calendar is because the two calendars are based on different laws of celestial motion.
Qi Rui, deputy director of the Beijing Planetarium: The Gregorian calendar is derived from the observation of the movement of the sun. Therefore, the cycle of the Earth's revolution around the Sun is called the return year in astronomy, and this length is the determining factor for the length of the Gregorian calendar. Astronomical observations, we know that the length of the return year is 3652422 days, so the length of this Gregorian calendar has to be approached to this value. From 2024, the Gregorian calendar is a leap year, and February has 29 days, so its length is 366 days. The lunar calendar should consider the movement of the moon, therefore, the length of each month depends on the change cycle of the moon phase, the cycle of the synodic month is a little more than 29 and a half days, so the length of each month of the lunar calendar is nothing more than 29 days or 30 days, the year of the dragon of Jiachen, it is a common year on the lunar calendar, it has only 12 lunar months this year, so the length of the year is 354 days.
How to calculate the number of days in leap years and ordinary years in the Gregorian calendar?
As mentioned earlier, there are 366 days in the Gregorian calendar in 2024 and 354 days in the dragon year in the lunar calendar, so how are these two numbers calculated?The Gregorian calendar is based on the Earth's cycle of movement around the Sun, which is a return year.
The length of a return year is 3652422 days, not a whole number, so in most cases, the Gregorian calendar has 1 leap year every 4 years. Leap years are leap years in which the number of Gregorian years can be divided by 4, with 29 days in February and 366 days in the year. Except for the endless year, which is a normal year, there are 28 days in February and 365 days in the year. The year 2024 can be divided by 4, so it is a leap year. There is also a special case here, if it is a full century year, such as 1800, 1900, 2100, it can be divisible by 100 but not by 400, and it is still a common year.
The number of days in the lunar dragon year, the length of each month of the lunar calendar is to see the cycle of the change of the moon phase, that is, the synodic month, a cycle of the moon is called a synodic month, with the length of the time interval from the new to the next new or from the look to the next look, with an average of 2953 days. There are 12 months in the year, with 30 days in the "big month" and 29 days in the "small month", and 354 or 355 days in the year.
The upcoming Jiachen year of the lunar calendar does not have a leap month, so it is a common year, and its corresponding Gregorian calendar date is February 10, 2024 to January 28, 2025, for a total of 354 days. So it's 12 days less than the 366 days in the Gregorian calendar in 2024.
How to calculate the common year and leap year of the lunar calendar?
The upcoming lunar Year of the Dragon does not have a leap month and is a common year. So how are the common and leap years of the lunar calendar calculated?There is a gap between the length of the lunar year and the Gregorian year, and in order to prevent the disconnection of the four seasons due to the difference in age, the ancients came up with a solution.
In order to reconcile the difference between the Gregorian calendar and the lunar calendar, the ancients used the "19 years and seven leaps" method to set leap months in 7 out of every 19 lunar years, so that there were 13 months and a total of 384 days in the year. This is the origin of the leap year in the lunar calendar.
Qi Rui, deputy director of the Beijing Planetarium: Nowadays, the leap year of the lunar calendar in our country is no longer in the ancient way, it is more scientific, simply called "when the leap is the leap". In fact, we know that strictly speaking, there is no such thing as a leap year, and there are leap months and leap days. What is the Gregorian calendar?Leap day. It adds an extra day to February, from 28 days to 29 days, so the year 2024 of the Gregorian calendar should be called a leap year, or leap year for short. And the lunar calendar, it is a real leap month, that is, if the year of the lunar calendar is a leap year, then there are 13 months in the year.
How are "big moons" and "small moons" divided?
In a year, the number of days varies from month to month, and people divide different months into "big months" and "small months" according to the length of the month. So how are the "big moons" and "small moons" divided?Is there a connection between the way the big and small months are divided into astronomy?
Qi Rui, deputy director of the Beijing PlanetariumThe "big month" and "small month" of the Gregorian calendar are completely artificially defined, the "big month" of the Gregorian calendar is 31 days, and the "small month" is 30 days, which has nothing to do with the astronomical law of the movement of the sun, moon and earth, it is a purely artificially defined quantity.
According to experts, the regulation of the length of the lunar month is related to the concept of "fixed Shuo". Dingshuo, that is, the day when the sun and moon are conjunct is set as the first day of the month. At this time, the Sun and Moon are at the same longitude on the ecliptic. The 29 or 30 days between the Sun and Moon conjunctions is the length of the lunar month.
Qi Rui, deputy director of the Beijing Planetarium: The movement of the earth around the sun and the movement of the moon around the earth are not uniform motions, their orbits are elliptical, which causes the length of the moon to be different from month to month. Therefore, we can only recognize the day of the new year, so the next occurrence (the first day of the new year) we will set the first day of the next month, and whether it is 29 days or 30 days in between depends on astronomical observations. How do we know if this month of the lunar calendar this year or next year is a "big month" or a "small month"?Be sure to look at the almanac released by the authority.
*: CCTV news client).