How to record the total solar eclipse in ancient times?

Solar eclipse is a natural phenomenon that has existed since the formation of the earth and the moon. After the arrival of mankind, the solar eclipse took on a new meaning. Solar eclipse has entered human history and become an important part of history. From recording solar eclipse to predicting solar eclipse, from believing that solar eclipse is a means for gods to intervene in human affairs to being able to explain solar eclipse scientifically, it has gone through a long history and many interesting stories have happened. Record of Eclipse The first solar eclipse in China is the most shocking astronomical phenomenon observed by human eyes, so human beings have paid more attention to solar eclipse since ancient times. China has a long and rich solar eclipse observation record. Chronicle of Bamboo Slips records the solar eclipses in autumn and September in the Five Years of Summer (about the 20th century BC), which is the earliest solar eclipse record found in the world. According to statistics, from the Spring and Autumn Period to the Qianlong period, there were about 1000 solar eclipses recorded in China history books, ranking first in the world. In ancient China, the main method of observing solar eclipse was basin reflection. This method was first seen in the battle of Kaiyuan in the first century BC. In the Song Dynasty, people used oil basins instead of water basins. Guo Shoujing in Yuan Dynasty can accurately measure the food fraction by pinhole imaging (food fraction is the ratio of the apparent diameter of the part of the sun covered by the moon to the apparent diameter of the whole sun). At the end of the Ming Dynasty, astronomer Xu Guangqi began to observe the solar eclipse with a telescope. Solar eclipse prediction is risky, and human beings have a long history of predicting solar eclipses. Because solar eclipse is endowed with profound political significance, one of the important duties of ancient royal astronomers is to predict solar eclipse. According to Andrew in Shangshu, He Tian, the royal celestial official appointed by Emperor Yao, failed to predict the solar eclipse because of his alcoholism, which caused confusion. This dereliction of duty brought him a fatal disaster, indicating that the solar eclipse had long been predicted. In the west, the Babylonians were able to predict the solar eclipse around 1000 BC (which may not be accurate, of course). Predicting the solar eclipse sounds great, but it can be done without modern scientific knowledge. First of all, its principle is not difficult to guess, because ancient astronomers tracked the trajectories of the sun and the moon all day, so it is easy to find that the moon will "invade" the sun during the eclipse, and thus infer the cause of the eclipse. Second, you don't need to know "Heliocentrism" to predict solar eclipse. In fact, from a kinematic point of view, it is no problem to say that the sun goes around the earth. Heliocentrism finally won because this statement is more concise and more in line with the explanation of Newtonian mechanics. We don't have to think that the earth revolves around the sun to predict the solar eclipse, as long as we can calculate when and where the intersection of the sun's orbit and the moon's orbit is. Of course, this calculation is supplemented by a large number of observation data. So, what kind of cosmic model did China use in ancient times, and how did it predict the solar eclipse? Feng, director of the Tsinghua University Institute of Science and Technology History, said that the celestial sphere model, which is basically consistent with the modern spherical astronomy model, was established in ancient China and is still relatively advanced. People in China have long known the relationship between the movements of the moon and the sun and the solar eclipse. The ancients in China discovered that all solar eclipses occurred in Shuori in the Western Zhou Dynasty, and studied the solar eclipse cycle in the Warring States Period, thus determining a set of formulas for predicting solar eclipses. The concept of time limit was put forward in the Eastern Han Dynasty, so the forecast was more accurate and precise, and of course there were times when the forecast was wrong. In modern times, by simulating the movements of the sun, the earth and the moon, the west developed instruments that can predict solar eclipses, but China did not use such instruments to predict solar eclipses in ancient times. So there are many successful examples of solar eclipse prediction in ancient times, and there are also many failed examples. Zhu Jin, director of the Beijing Observatory, said that the prediction of solar eclipse in ancient times was not very accurate because the universe model was not very correct and the calculation accuracy was not high. Of course, the current solar eclipse prediction is very accurate. Zhu Jin said that the prediction of solar eclipse no longer needs observation, and it can be accurately predicted by calculation, and it is fast and good to predict by computer. Although the orbits of the earth and the moon will change slightly due to the tiny gravity of tides, asteroids and distant celestial bodies, this change has little effect on solar eclipse prediction. Misreporting solar eclipse is a good thing. It is recorded in the Book of the New Tang Dynasty (Volume 27) and Chronicle III. At that time, the official in charge of astronomical observation and calculation reported that there would be a solar eclipse in December of the thirteenth year of Kaiyuan. In ancient China, people mistakenly thought that the solar eclipse was an "immoral" warning and punishment to the emperor, so emperors usually tried to rescue them when they heard such reports. At that time, Emperor Xuanzong of the Tang Dynasty was on his way back to Beijing from Mount Tai, and he used fasting and simple clothes to remedy it. Who knows, at the time predicted by Tiangong, the solar eclipse did not happen! If we put this matter aside now, we will say that Tiangong has miscalculated. But at that time, it was a great event, and ministers excitedly thought that the emperor had a sense of morality and congratulated him. This leads to an interesting topic. If the solar eclipse is predictable, then it is just a natural phenomenon like the 24 solar terms, and it is difficult to connect with political activities, then the role of "celestial officials" will decline; But if it is completely unpredictable, "Tianguan" will become a simple recorder, and their status will also decline. So how can their status be maintained in a long historical period? The astronomer monk and his team in the Tang Dynasty were very clever people. He told the truth in one sentence: "If you can't find a constant of solar eclipse, you can't calculate the density of the calendar;" If everything stays the same, the rest of politics and religion will be unknown. "That is to say, if the eclipse is completely irregular, the accuracy of the calendar will be impossible; However, if there are laws to follow in every lunar eclipse, it is impossible to know God's attitude towards the advantages and disadvantages of human politics. In other words, there are predictable factors, unpredictable factors, or factors that can be temporarily changed by human power, which is a bit like gambling and a bit like pursuing beautiful women.