"But ordinary stars are also quite interesting. We found that the stars in the sky may be bigger than we imagined. The reason why they look small is because they are too far away." Shi Shen said while writing. In the past, only two stars could be seen in the sky. There are more than a thousand stars. Since the advent of telescopes, the number of stars has suddenly doubled.
Although this telescope is far behind the astronomical telescopes of later generations, in this era, it is already an artifact level thing.
"The "Zhou Bi Suan Jing" calculated that the distance from the sun to the center of the earth is 80,000 miles, and the distance to the royal city is 100,000 miles. But after our recalculation, the difference in the length of the sun's shadow is one inch, and every difference of one thousand miles between north and south It's wrong. Different places and different time periods also have an impact on the length of the shadow."
"The difference between summer and winter is very big. And... the method in "Zhou Bi Suan Jing" is based on the calculation that the ground is flat. If the ground is a ball, then the method used in "Zhou Bi Suan Jing" is wrong . We suspect that... the distance from the sun to the ground is not fixed, but changes back and forth in annual cycles, which also explains why there are spring, summer, autumn and winter," Gander said.
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In order to study these things, he and Shi Shen, two old men, even listened to Zhao Kuo's lectures on physics and mathematics every day, more seriously than when they were young.
In the past, the two of them always said that they had enough life, but now they complain about not having enough time every day.
"You mean the sun is moving back and forth? Or is it moving up and down?" Yin Gao's thinking couldn't keep up with Gan De's.
"We suspect... that the sun is stationary and that the earth is revolving around the sun. Because according to our calculations, the diameter of the sun is ten to fifteen times that of the earth and forty to fifty times that of the moon (error)." Gan De whispered, he only dared to say it in front of Yin Gao, if he said it in front of other people, he might be tied up and burned to death.
"Then how do you explain that the sun rises from the east and sets from the west?" Yin Gao asked calmly, without any disturbance in his heart, and even wanted to eat a date.
He would not be surprised at anything that came out of the mouths of these two old men.
"If the earth is a ball and it is rotating around a certain axis, it can be explained." Gander took out a date from the basket, raised it in front of him, released his fingers, and the date fell to the ground.
"But this explanation cannot explain why the dates fall straight on the ground instead of falling to the west. Just like there is no way to explain why the dates fall to the ground instead of flying away after being thrown. So we just Speculation, there is no way to prove it yet.”
If it can be proven that he has already written a book and announced his new discovery to the world, as long as he can dismiss everyone, he will be a great master in the future. But now I can only hold it in for fear of being regarded as a heretic by others.
"If the earth is spherical, rotating around the sun, and the distance is not fixed, then there is no way to calculate the distance from the ground to the sun." Yin Gao said.
"There is a way." Gander took out a piece of paper from the side, and drew a picture on it, as well as three small balls, representing the sun, the earth, and Venus respectively. Below is a lot of calculation processes, densely packed, and there are many more on the table. .
"We have calculated that the distance from the ground to the sun is five times (error) from the ground to Taibai (Venus). When Taibai (Venus) transits the sun, we will observe the Taibai transit at the same time at two locations thousands of miles apart. This At that time, the Taibai positions observed at two points are different, and then the distance between the two points can be inferred based on the difference in duration of the Taibai transit observed at the two places."
"Using the distance between two places on the earth, calculate the distance from the black spot formed by Taibai on the sun. Based on the multiple of the black spot and the sun, we can calculate the diameter of the sun. Then based on the angle, we can calculate the distance from the sun to the ground. distance."
"As for the time problem, we can use the latest clock made by the Mo family to solve it."
More than a hundred years ago, Mozi invented a rotating roulette wheel, which was the prototype of the wheel pod later invented by Zhang Heng. However, Mozi later threw it away as he thought it was useless, and Zhang Heng only used it as a calendar. But this thing can be used as a clock with a few modifications, and its accuracy is already considered first-class in this era.
"Taibai transits the sun!" Yin Gao himself was also a first-class astronomer and mathematician at that time. He understood the principle after a little thought. It is hard to say whether it can be realized in practice, but there is no problem in theory. The problem now is ——When will Taibai Lingri come?
"The most recent record of a transit of Taibai was in the tenth year of King Zhou (305 BC, according to the time calculation, the transit of Venus will indeed occur in this year). The comet passed across the sky, and there was no trace of it. After a while, the phenomenon of Taibai Ling sun appeared. Tang Mei of Chu State recorded it. It has been nearly fifty years ago. Who knows when the next Tai Bai Ling sun will be?" Yin Gao shook his head.
Although they discovered the phenomenon of Taibai transiting the sun, they did not summarize the rules.
"We may not live until that time, but you are still young and there is still hope. The descendants of our two families have no talent in this area, so we have to rely on you. When the results come out, go to our two graves Just tell us beforehand." Gander said with a sigh.
Even those who have the most profound research on astronomy today do not know how many years a Taibai transit will occur, and they are not even sure whether this method is feasible.
During the Shang and Zhou dynasties, there were dedicated officials to record such celestial phenomena. However, due to wars, these ancient books have been lost for a long time.
In the past, Gan De and Shi Shen would definitely leave this issue to future generations. In this era, what the ancestors told them before they died must be completed even if they are not dead.
But after meeting Yin Gao, he decided to leave the problem to Yin Gao.
After all, compared with Yin Gao, his descendants are useless. Even if they are really desperate, they may not make much progress, and Yin Gao is the only descendant who has the possibility to reach the heights of him and Shi Shen.
What he didn't know was that the next transit of Venus would have to wait until seventy-five years later. If nothing unexpected happened, the grass on Yin Gao's grave would be several feet high, let alone him.
"Can't we use the transit of Chenxing and Mercury to calculate it?" Yin Gao said with a frown.
"The stars are too far away from the earth, and the parallax we see is too small. I'm afraid we can't accurately calculate it at our level. Even if we use Taibai Transit, there will be a lot of error." Shi Shen shook his head.
He has long thought of using the transit of stars to calculate, but on the one hand, it has been two years since the last transit of stars (it should be this time), and he doesn't know when the next one will be.
On the other hand, as Shi Shen said, the distance is too far and the error is too large. It is impossible to calculate at the current level.
"If I can encounter it, I will definitely try my best to complete it." Yin Gao said solemnly.
