Everyone knows that there is a leap year in four years, so why can only be divided by four hundred years to be considered a leap year

When we were in school, the teachers taught us such a problem. Each year is not necessarily 365 days, and if you encounter a leap year, it is 366 days. A leap year is a leap year in four years, a leap year that can be divided by four AD numbers, and a flat year that cannot be divided by four. Because a year is not a full 365 days, it is 365.25 days, after four years, there will be one more day, so four years a leap. If the number at the end of the AD is two zeros, it cannot be divided by four wholes, and it must be divided by four hundred to be considered a leap year. Any number with two zeros at the end can be divisible by four, but some cannot be divisible by four hundred, and if it cannot be divided by four hundred, you open the perpetual calendar of that year and find that February of that year is only 28 days.

Speaking of which, then the question arises. Since the year is 365.25 days, it must be a leap every four years. So why is it that at the end of the AD number is two zeros that can be divided by four hundred to be considered a leap year. For example, in 1900, the previous year 1896 and the later 1904 were leap years, if 1900 was a common year, the four-year leap rule would be broken and become an eight-year leap. Isn't a year of 365.25 days, and a leap of eight years, that's not less than one day? If you ask the teacher when you are in school, then the result for you is a sentence in the "Two Children's Debate Day", and Confucius cannot decide it. Some teachers think that a leap year is a four-year run, and they regard 1900 and 1800 as leap years, so they mislead many children.

Speaking of this, some people will say, even if you do this, you have to die a lot of brain cells, what is the meaning of drilling this horn tip. Of course, when he said this, he thought it couldn't be calculated, and when people said so, he believed it. In fact, why the whole hundred years divided by four hundred is a leap year, it can be calculated, otherwise I would not drill this horn tip, to be honest, drilling the horn tip is really meaningless. In addition, many students, including many adults now, do not know this reason, and only think that 1900, 1800 is not a leap year, which belongs to the bad rules, including the teacher who misled the children above. But some people want to know the reason, but they are said to be drilling the horns.

Then, we will answer the question that the teacher did not answer that year, and reveal that the number at the end of the AD is two zeros, which can only be divided by 400 to be considered a leap year.

First of all, in the ancient calendar and the Zhou Yi eight-character prediction, the year is based on Lichun as the node, and the Lichun of that year to the Lichun of the following year is a year. This question was mentioned in my previous article "Everyone with shoes, do you know what the birthday Eight Words mean", if you are interested, you can pay attention to my collection browsing. Since the intersection of Lichun is the beginning of a new year, Zhou Yili has the smooth slip of pushing Lichun, that is:

Whatever the difficulty of the method of pushing the knot, the root cause is set on the spring day.

Plus five days and three o'clock, the following year's spring time.

The meaning of this slip of the tongue is that knowing the date and hour of the spring of the year, you can calculate the date and hour of the other eleven festivals through the spring of the year. So why add five days and three o'clock is the time of the following year's spring? Is it true that the spring time in 2021 is 22:58 minutes and 39 seconds on February 3, and the spring in 2022 is 04:58 minutes and 39 seconds on February 9. Wrong, big mistake, very wrong, not to mention that the time of 2022 is not February 9. The five days mentioned here are the heavenly stems and earth branches of the pillar of the day plus five days. Because there are 365 days in a year, there are a total of 60 pairs of Tiangandi branches, and 360 is exactly a multiple of 60, so from the beginning of Lichun to the 361st day of Lichun, the daily stem branch is the same, and the tiangandi branch enters five places, which is the daily stem branch of the year's Lichun.

Speaking of this, someone should ask, is it necessary to add six days and three hours when you meet Rui Nian, no. As we said just now, the ancient calendar year was based on Lichun as the node, and at that time there was neither a common year nor a leap year. And midnight does not mean that the new year is observed, and the intersection time of spring is the beginning of the new year. Generally speaking, there are three hours in 365 days from the spring of the following year to the spring of the following year, which is now six hours.

So, is a year really 365 days and six hours, that is, 365.25 days? Obviously not, if it were, I wouldn't need to write this article, because in this case, the whole hundred years would be a leap year. As we just said, the spring time in 2021 is 22:58:39 on February 3, then the spring time in 2022 is 4:50 minutes and 36 seconds in 2022, and the time of 2021 is 365 days, 5 hours, 51 minutes and 57 seconds. Speaking of which, some people calculate it like this, 365+ (5×3600+ 51×60 + 57) ÷ (24×3600) ≈ 365.2441 (days), so use this number to find, the whole hundred years is not a leap year. This is obviously wrong, due to the action of tidal forces and various magnetic fields, there will be some errors in the time it takes for the Earth to orbit the sun. For example, the spring time in 2023 is 10:42:21 on February 4, so the time of 2022 is 365 days, 5 hours, 51 minutes and 45 seconds, and you can see that the time of 2021 is 12 seconds more than 2022.

This is the 2020 to 2030 Spring Schedule, and you can calculate the real time of each year through this table.

Spring schedule from 2020 to 2030

Through everyone's calculations, it is found that the time of the year is between 365 days and 5 hours and more than 40 minutes to more than 50 minutes, so the value of 365.25 days a year is not available at all, and there will be a big gap in the long time. Of course, in order to seek a hundred years is not a leap year, a year is not advisable, you from life to death, you may not be able to calculate a thousand years. So over the course of the year, the gap gets an average of 365.2425 days a year. It is possible that a year will be greater than 365.2425 days, it is possible that a year will be less than 365.2425 days, and it is possible that a year will be exactly equal to 365.2425 days. This average, there is also a gap, but it is the smallest. If you achieve zero gaps, one is that there is no time, and the other is that there is no energy. After all, the longitude and sunrise and sunset times are used in the normal solar time, except for the real sun time in Tiananmen Square, the other time with the real sun is not necessary, after all, it is not the national flag.

At this point, some people will ask, the extra time is not enough for six hours, why do you have to say "plus five days and three hours, the next year's spring time". Because in the ancient legislation and the eight-character plate, there was a faction called the blind faction. Since the blind people could not read the perpetual calendar, some old jianghu righteous people made up some festival and fixed law songs. Different schools of thought, the festivals and songs are also different. I found a more accurate method of setting the festival and singing the spring and saying it to everyone, just to prove that it took more than a year. In the ancient calendar and the arrangement of eight characters, it is not so precise, as long as it does not make an error of more than one hour. The time of 2021 is 22:58 minutes and 39 seconds, which belongs to the time of the sea. At nine o'clock in the evening, the year pillar and the moon pillar changed. The spring time in 2022 is 4:50:36 seconds, and the hour plus three hours is exactly the time of yin. Therefore, it is also feasible to say that "with the addition of five days and three hours, the next year's spring time" is also feasible.

Well, here's the point. From the above statement, we know that the year is 365.2425 days, an additional 0.2425 days, and then we use these data to calculate why the whole hundred years that can be divided by four hundred are leap years.

0.2425 more days a year, a leap in four years, a few more days?

0.2425×4=0.97 (days)

Four years is 0.97 days more, and if the leap year of the fourth year is one more day, it will be calculated by the formula and you will find that there are 0.03 days less.

1-0.97 = 0.03 (days)

Four years are 0.03 days less, and there are 25 four years in a hundred years, and if the first hundred years are also regarded as leap years, one hundred years is 0.75 days less.

0.03×25 = 0.75 (days)

After all, there is almost a day less, so the first hundred years cannot be a leap year, if you look at the first hundred years as a flat year, in a hundred years, there will be more time.

1-0.75 = 0.25 (days)

According to the formula, if you think of a hundred years as a common year, this hundred years will be 0.25 days more. A hundred years more than 025 days, four hundred years is exactly one more day, so the fourth hundred years is exactly one more day, so the fourth hundred years is a leap year.

0.25×4=1 (days)

Why should we regard what can be divided by four hundred as a leap year, because in a whole hundred years, every four hundred years of the AD number can be divided by four hundred years, and the leap year of the whole hundred years is four hundred years and one leap year, and in this way, it is convenient for us to distinguish between the ordinary year and the leap year of the whole hundred years.

Of course, you can also calculate that there are 0.75 more days in a year, so how many days is more than four years?

0.75×4=3 (days)

It is exactly three days, so in order to facilitate the distinction, we can only turn the whole hundred years into a flat year, and there are exactly three whole hundred years that cannot be divided by four hundred, so for our convenience in distinguishing, we will turn the whole hundred years that cannot be divided by four hundred into a flat year, and the one that can be divided by four hundred into a leap year.

Speaking of this, I don't know if you old iron understand it. If you can't understand it, it may be that my writing is limited, and what I write is unlikely to be understood by everyone. If you old iron do not understand and are interested in this issue, you can pay attention to me, and I can tell you with words that make you understand. In addition, pay attention to me, and will update more interesting and more revealing works in the future.