In a room of the Taishi Bureau of the Tang Dynasty, a young official in his twenties was busy at his desk.

On the desk, there are three keju, as well as messy papers and calculation chips.

The official fiddled with the three bows for a moment, and pondered with his brows; After a while, he fiddled with the calculation plan and did the calculation; After a while, he wrote and drew on the paper again.

"Yes, that Zhao Yunze is right, the solar and lunar eclipses are indeed formed in this way." After being busy for a while, the official stopped his movements, nodded and muttered to himself.

After thinking for a while, the official's eyes lit up, and he immediately continued to get busy.

After a long time, the official suddenly dropped his pen in discouragement and said, "No, no, if the solar and lunar eclipses are indeed formed in this way, I should be able to calculate the date of the next solar eclipse, why can't I start?" I remember that it is recorded in the history books that Zhang Heng of the Han Dynasty once accurately calculated the date of a lunar eclipse, and what he could do, could I not do it? ”

After thinking for a while, the official shook his head and said, "Yes, Zhang Heng only calculated the date of the lunar eclipse, but not the date of the solar eclipse. It seems that it is easier to calculate a lunar eclipse than a solar eclipse, so I'll try to calculate the lunar eclipse first. ”

After speaking, the official took out a thick book, and began to examine it carefully from the last page of the book.

"Found it, this is the date of the recent lunar eclipse."

The official was immediately busy at his desk again.

Before you know it, another hour has passed. The official threw his pen again and sighed: "It's still not possible, I can't figure it out at all." ”

After thinking alone for a while, the officer stood up and hurried out of the house.

"Master Li, you haven't dispersed yet, where are you going?" At the gatehouse of the Taishi Bureau, a small official asked the young official.

"I went to the military department for something." The official dropped a sentence without looking back, and walked out of the gate of the Taishi Bureau.

"This Li Chunfeng is in a hurry to do anything." The porter shook his head and sighed.

It turned out that this official who had just left the Taishi Bureau was Li Chunfeng, who was famous in history.

When Li Chunfeng is mentioned, it is easy for future generations to associate the word "god stick". This is mostly influenced by romance novels and later TV dramas.

However, the real Li Chunfeng in history is not just a magic stick. Although Li Chunfeng is also very good at divination and divination, his greatest achievement is in astronomical calendar and arithmetic.

Historically, Li Chunfeng joined the army as an official in the Qin Palace, and later joined the Taishi Bureau, from the lowest level of the general Shilang all the way to the Taishi Ling, almost all his life has been dealing with the astronomical calendar and arithmetic. In these two aspects, many heirlooms have been left behind, and great achievements have been made. Yang Weizhen of the Ming Dynasty praised Li Chunfeng and said: "Those who know the astronomical calendar in ancient and modern times should be the first to recommend Li Chunfeng."

Li Chunfeng, who has been in the ninth year of martial arts, is just twenty-four years old. At this time, he had just joined the Taishi Bureau, but his attainments in the astronomical calendar had already attracted wide attention from the government and the opposition. In addition, he was from the Qin Palace, so Li Shimin informed Li Chunfeng of the causes of the solar and lunar eclipses that he had just learned from Zhao Yunze.

Just now, Li Chunfeng was verifying and absorbing this new theory of Zhao Yunze.

When Li Chunfeng arrived at the military headquarters, Zhao Yunze was organizing the trainees of the training course of the Arsenal Special Administration to conduct a queue training.

Seeing that someone was looking for him, Zhao Yunze stopped training and let the trainees rest in place.

Zhao Yunze looked at the person who came, very unfamiliar.

"A certain is the Taishi Bureau's general Shilang Li Chunfeng, disturbing Lord Zhao." Li Chunfeng said to Zhao Yunze.

Li Chunfeng? The god stick? How did he find me? "I don't know if Master Li is looking for something, what advice do you have?" Zhao Yunze asked Li Chunfeng with doubts.

"Lord Zhao can call a certain table to be new and harmonious." Li Chunfeng was humble for a moment, and immediately got straight to the point: "Lord Zhao, because of the cause of the solar and lunar eclipse, I have come to ask you for advice. ”

Zhao Yunze was stunned: "Your Majesty told Yu Xinhe what I said to him?" ”

Li Chunfeng nodded and said, "It is the new theory of the causes of lunar and solar eclipses that I learned from Your Majesty. A certain person calculated it again today and thought that this statement of Lord Zhao was valid. ”

Zhao Yunze said happily: "Of course it is true, I have deduced it after countless calculations." ”

Calculus deduces a fart, you are borrowing flowers to offer Buddha.

Li Chunfeng said again: "However, there is also a question. According to Lord Zhao, it should be possible to calculate the exact dates of the lunar and solar eclipses, but after being busy for nearly a day, he got nothing. I don't know if Lord Zhao has a method of calculation? ”

Yes? Let me calculate when a lunar and solar eclipse will occur? It's a joke, if I really have this ability, I don't have to be a soldier. Alas, people don't pretend to be forced, pretend to be forced to be struck by lightning, retribution is coming so fast!

"This ...... It's difficult! Zhao Yunze said ambiguously.

"It's difficult?" Li Chunfeng frowned, and then his eyes lit up and said, "In other words, Lord Zhao knows how to calculate?" ”

I squeezed myself and put myself in. Zhao Yunze really wanted to suck himself in a big mouth. Tell your mouth to owe! Tell your mouth to owe!

"Well, I just have a general direction." Zhao Yunze thought about it for a while and decided to give Li Chunfeng a problem.

"Please also ask Lord Zhao to give me advice!" Li Chunfeng gave Zhao Yunze a deep salute.

"In order to estimate the time of the occurrence of lunar and solar eclipses, it is not enough to know the causes of the two, but also to know the respective trajectories of the sun, the moon, and the earth and the position of each other."

Li Chunfeng thought for a while, nodded and said, "Yes, it is only calculated based on the fact that the moon rotates around the earth for 29 days, no wonder there is no way to start." ”

Zhao Yunze was surprised: "Who told you that the moon revolves around the earth for 29 days?" ”

"Isn't it? The calendar used today is based on the cycle of the moon. Li Chunfeng wondered.

Zhao Yunze smiled and said, "However, the calendar used now is not accurate enough." In fact, the moon orbits the earth for 27 days and a little more than three hours; The Earth's orbit around the Sun is 365 days and a little more than two hours. ”

"Lord Zhao, where did this come from?" Li Chunfeng said in surprise.

Uh, where did it come from? Learned from 21st century secondary school geography textbooks.

"Well...... It was my master who told me. "Zhao Yunze has once again launched the flickering magic skill." Don't ask. Anyway, if you follow the data I said, and then observe and calculate the orbits of the sun, the earth, and the moon, you should be able to calculate the dates of the lunar and solar eclipses. ”

Take your time and observe the calculus, and without a few years of work, you're afraid you won't be able to figure out this problem. I have more than a thousand years of knowledge more than you, and I haven't figured it out yet, right?

"That'...... Did Lord Zhao ever know the trajectory of the sun, the earth, and the moon? Li Chunfeng asked again.

Zhao Yunze shook his head and said, "I have also tried to observe and calculate, but I have not obtained anything. Now that he is working in the arsenal of the Ministry of War, it will be even more difficult to find time to observe and calculate this problem in the future. Everything depends on Xinhe and Brother himself. ”

He's observed a ghost! It is again to fool the dead and not pay for their lives.

Li Chunfeng arched his hand at Zhao Yunze and said, "Thank you Lord Zhao for your advice!" ”

"Brother Xinhe, when I met you today, I remembered something." Zhao Yunze said, "The day before yesterday, I talked to Your Majesty about attaching importance to other hundred schools of thought besides Confucianism. A certain suggested to His Majesty that an academy of sciences be established to specialize in the study and teaching of miscellaneous sciences. His Majesty should also approve it, and when the time is right, he will plan to establish an academy of sciences.

This astronomical calendar and arithmetic also belong to a kind of science of things. Brother Xinhe is a great power in this regard, if the Academy of Sciences is established in the future, I want to invite Brother Xinhe to withdraw to the Academy of Sciences and serve as a guest lecturer, I wonder if Brother Xinhe can be invited by a certain person? ”

"What, it's great to set up an academy that specializes in teaching the study of things!" Li Chunfeng became excited, "If you can carry forward the astronomical calendar and arithmetic, I am willing to help Lord Zhao." ”

Zhao Yunze nodded with satisfaction and said, "Then let's make an agreement first, just wait for the establishment of the Academy of Sciences, and Brother Xinhe will come to the Academy to teach." ”

As soon as Zhao Yunze finished speaking, he suddenly heard two coughs behind him. When he looked back, he saw Du Ruhui standing two or three meters behind him with a dark face.

"Master Du, why don't you make a sound when you walk, people are scared to death!"

"Peng Yu, something happened to the Turkic Mission of the Sifang Pavilion!" Du Ruhui said with an ugly face.