In the Wenhua Hall, the emperor and his ministers watched in amazement as Zhao Hao used the model of the solar system to demonstrate the causes of solar eclipses, lunar eclipses, and moon phases.

But to be honest, apart from the moon phases which need no proof because the waxing and waning of the moon is there, it is still hard to believe that the causes of solar and lunar eclipses are so simple.

It clearly demonstrates why a solar eclipse only occurs on the first day of a lunar month, and a lunar eclipse only occurs on the fifteenth day of a lunar month.

However, this little evidence is far from enough to convince the public.

As a result, everyone's eyes were all turned to Bei Peijia, the director of the Imperial Observatory, hoping that this old hermaphrodite with a rich family background in hermaphroditism could answer everyone's questions.

Bei Peijia spread his hands helplessly. It was the first time he heard that the earth revolved around the sun.

Zhao Hao, who understood everyone's psychology, said, "Until now, you will definitely ask, what is the difference between this and Xunzi's 'Theory of Heaven'? They are both just hypotheses."

The officials nodded with a smile and said yes.

As Zhao Hao said, in their view, the so-called "solar system" is just a hypothesis. There is no essential difference between it and the "Huntian Theory", "Gaitian Theory" and "Xuanye Theory", which are all just hypotheses.

It's a hypothesis, believe it if you want, forget it if you don't. So they didn't care too much, just taking it as a novel experience.

"But what I want to tell you is that this model is not something imagined, but is derived from detailed observational data and precise calculations."

Then Zhao Hao said in a shocking voice: "So we can use this as a basis to calculate the time and observation direction of every solar and lunar eclipse, as well as various celestial phenomena such as Venus conjunct the moon and Mars conjunct the heart."

"Can you calculate it accurately?" Bei Jianzheng couldn't help but shout out, "You are just bragging!"

The censor who was maintaining order was about to shout a rebuke, but when he saw Lord Xu shook his head slightly, the censor shut up obediently.

The day before yesterday Lord Xu summoned Bei Jianzheng to the cabinet to give him instructions, and today he wants him to take the lead!

"Is this strange?" Zhao Hao said proudly with a look of "this question is so stupid":

"Astronomy has been called the science of astronomy since ancient times. Isn't it based on observation and calculation? Liu Hui of the Western Jin Dynasty wrote the Sea Island Mathematical Classic, which clearly described the methods. Zu Chongzhi of the Northern and Southern Dynasties could accurately calculate the orbits of the five planets, Jupiter, Mercury, Mars, Venus, and Saturn, and the time required for one orbit, as well as the more accurate conjunction period of the five planets. Even Guo Shoujing of the previous dynasty could calculate the obliquity of the ecliptic..."

"Speaking of Guo Shoujing, can't the previous dynasty's "Shushi Calendar" be used to predict solar eclipses? It just lacks accuracy." He looked at Bei Jianzheng in surprise and said:

"It's hard to imagine that a director of the Imperial Observatory would ask such a question."

Bei Jianzheng's face immediately turned red as Zhao Hao hit the nail on the head, because this was the fatal flaw of the Ming Dynasty's Imperial Observatory.

He knew that the Shoushi Calendar could predict solar eclipses, but he just couldn't understand it...

Because there was a gap in mathematics during the Ming Dynasty!

As mentioned before, in the middle of the Yuan Dynasty, China's world-leading mathematics declined sharply.

In addition to the reasons of cultural regression and neglect by scholars, the popularity of abacus during this period caused the ancient mathematical system based on counting to fall apart, and the four elements, Tianyuan, Dayanqiuyi, and increase and multiply square root were completely lost in this dynasty.

Without these mathematical tools, the Imperial Astronomical Observatory could not understand the "Shushili" calendar derived from the Tianyuanshu, and the solar and lunar eclipses they calculated based on the current "Datong Calendar" were full of errors and had completely lost their reference value.

As a result, the Imperial Observatory is generally believed to be a simple institution for observing astronomical phenomena.

In the eyes of the officials, their daily work was to look up at the sky, record unusual celestial phenomena, and then consult and compare divination books, copy the books and submit them to the court. It did not require a high level of knowledge, as long as they could read.

Bei Jianzheng was very angry about this - at least compiling the imperial calendar every year still requires a lot of technical skills!

~~

Therefore, Bei Jian blushed for a while before gritting his teeth and said to Zhao Hao: "Yes, I can't figure it out, but I believe that no one in the entire Ming Dynasty can figure it out!"

"I can do it." Zhao Hao smiled faintly and said, "And my disciples can do it too."

"Then calculate it!" Bei Jianzheng laughed and said, "If you can really calculate it, I will worship you as my master on the spot, so what?"

"You are taking advantage of me." Zhao Hao said arrogantly. "It's not easy to become my disciple."

Li Gelao and Chen Gelao agree with this. Their sons are still solving geometry problems at home...

"Zhao Hao, what do you think this place is?!" The young elder finally couldn't help himself and shouted, "Stop being so presumptuous here!"

"You are the one who is being presumptuous, aren't you, young minister?" Zhao Hao sneered and glanced at him, "Don't you know that interrupting others is very rude?"

"you!"

"Quiet!" Seeing that the censor's mouth was tied, Teng Xiang had no choice but to scold him: "Don't make noise, talk properly."

Zhao Hao then turned to Bei Jianzheng and said, "For your Majesty's sake, I will make an exception and accept you as my registered disciple."

"You figure it out first!" Bei Jian was at a loss whether to laugh or cry, thinking to himself that I, a fifth-rank official, was actually looked down upon by a mere attendant.

It is true that there are many crazy people among the waiting officials.

"Okay, given your limited math skills, I'll teach you a simple algorithm." Zhao Hao cleared his throat and said loudly:

"I have just demonstrated that solar and lunar eclipses are caused by the movement of the sun, earth, and moon to special positions. The movement cycles and orbits of the earth around the sun and the moon around the earth are regular, so the occurrence of solar and lunar eclipses must also follow a regular pattern."

"Astronomers in the Han Dynasty called the Earth's orbit the ecliptic and the Moon's orbit the white path. They have also discovered that the two are not on the same plane, but rather there is an angle of 5 degrees and 9 minutes between the ecliptic and the white path." Then Zhao Hao pointed to the orbits of the Earth and the Moon on the model and said:

"Now, let's look at the conditions for a solar eclipse to occur - it can only occur on a new moon, and the sun and moon must be more or less in a straight line."

As he spoke, Yu Shenxing arranged the relative positions of the sun and the moon during a solar eclipse on the model.

"You can see that when a solar eclipse occurs, the sun and the moon must be near the intersection of the yellow and white points." Zhao Hao said, and he and Yu Shenxing pushed the three small balls to rotate along the track:

"If many days pass and the sun and moon move to almost the same position again, a similar solar eclipse will be observed on Earth."

The astronomy of the Ming Dynasty was indeed a mess. This was common knowledge in the Han Dynasty. Only Bei Jianzheng and his deputies could keep up. The eyes of the rest of the people were already distracted, just like you who saw this...

Seeing that Bei Jian was nodding, obviously he understood, Zhao Hao was slightly relieved and continued:

"So as long as we have the time it takes for the sun to pass through the intersection of the ecliptic and the time it takes for the moon to pass through the intersection of the ecliptic and the intersection of the ecliptic twice in a row, and then find the least common multiple of these two numbers and the number of days in each month, we get the number of days required to repeat it once!"

"An average month is 29.53 days. A nodal month is 27.21 days. An eclipse year is 346.62 days."

The data on nodal months and eclipse years have existed since ancient times, and Bei Jianzheng can recite them off the top of his head.

Obviously, the uncle is not just here to eat and do nothing.

"Then can you calculate?" Zhao Hao asked hopefully.

Bei Jian was shaking his head, tears were about to fall.

"Okay, I'll teach you." After all, Mr. Zhao liked to teach others, so he taught him step by step how to decompose prime factors.

Unexpectedly, the uncle taught him how to do it, and he immediately picked up the pen to calculate. After a while, he reported the number: "It should be 6,585 and one-third days."

ps. First update, haven't finished checking it yet, please post it slowly... Please give me monthly votes and recommendation votes~~