Gold-inlaid pearl celestial globe, made during Qianlong period.
armillary sphere
The name armillary sphere is naturally associated with Zhang Heng in China. This scholar, who lived in the 2nd century AD, not only made the most famous armillary sphere in China's history, but also used his wise brain to answer the question of why the universe exists-although his answer is definitely different from the standard answer. In his book Lingxian, he explained that before the birth of all things in the universe, it was a state of "static and motionless, silent and silent, unable to be an image, but hollow and nothing outside", which was called "Xuan". The initial stage of the universe is a "magnificent" state of "germination without warning, chaos of the same color". Finally, "vitality is judged, just divided, turbidity is different." The state of this stage is called Taiyuan. Thus, human beings were born. Among them, the "human essence" is those guys who are called "saints". They look up to astronomy and geography as a discipline and learn from heaven and earth.
In the era when there was no telescope, how Zhang Heng and his colleagues discovered these principles only by naked eye observation has always been a mystery. The armillary sphere he made is a model of the universe created according to his ideas. The cosmology of Zhang Heng's era is mainly divided into two theories: Huntian theory and Gaitian theory. The theory of "covering the sky" first came into being, and its theory has changed twice. From the earliest "the sky is like a cover and the earth is like chess" to "the sky is like a hat and the earth is like a purlin" in the Warring States Period. From the chess game to the upside down, the curvature of the earth is getting bigger and bigger until it is considered that the curvature of the sky is basically the same as that of the arch. The reason why the radian increases again and again is that it is increasingly difficult for horizon theory to explain the difference between theory and astronomical observation. Thus, Huntington theory came into being. In the Huntian theory, the earth is no longer entangled in radians, but is surrounded by a spherical Huntian. Although, in the eyes of modern people, China's theory of Huntian is no different from the western geocentric theory, and it is the wrong view of the universe of the ancients, at that time, a qualitative step has been taken from heaven to earth.
Porcelain green paper astrolabe was made by the court during the reign of Kangxi.
Gaitian theory and Huntian theory
Although Zhang Heng is considered as a master of Huntian theory in Han Dynasty, he lives in an era when Huntian theory and Gaitian theory coexist. At that time, Zhou Kuai Shu Jing, the most important mathematical work, was based on Gaitian Theory, and even Zhang Heng should learn from it. Therefore, his description of the structure of heaven and earth in Lingxian is vague, that is, "the sky is outside, the earth is inside" and "the sky is round and moving". This is the theory of Huntian, but he also wrote "the ground is flat and quiet" and "the scenery hanging in the sky and the devices on the thin ground all move a thousand miles and an inch", which is another theory that covers the sky.
However, in the biography of Huntianyi written by Zhang Heng, Zhang Heng seems to be a thorough school of Huntianyi theory. He wrote, "The sky is like a chicken, the celestial body is round like a projectile, the rehmannia is like a chicken, lonely, big and small ... The sky turns like a hub, and it is endless and muddy, so it is called the sky." However, this account was quoted by Ge Hong in Jin Dynasty. Considering that this famous Taoist priest has many criminal records of forging books in the name of celebrities, it is doubtful whether Notes on the Huntianyi is really written by Zhang Heng.
However, the biggest difference between Huntian theory and Gaitian theory lies not in the shape of the earth, but in the operation of the sky. Gaitian said that the sun, moon and stars revolve around a center above the earth; Huntian theory holds that the celestial sphere wraps the earth, the sun, the moon and the stars are attached to it, and the celestial body will follow the celestial sphere to the bottom or back of the earth. Whether the earth is flat or round, at least in Zhang Heng's time, is not the focus of debate.
The armillary sphere, as its name implies, is a model of the universe based on the theory of armillary sphere. The armillary sphere we see today is a hollow sphere nested with many rings, which imitates the celestial sphere and is carved with fine patterns. You can see it as long as you go to Nanjing Purple Mountain Observatory. Although this armillary sphere made in Ming Dynasty is theoretically a disciple of Zhang Heng's original armillary sphere, there is no small difference between them. The armillary sphere in Ming Dynasty needed manpower to run, while the armillary sphere made by Zhang Heng was driven by water. The biggest difference is that the armillary sphere we know today is an instrument for observing celestial phenomena, while the armillary sphere made by Zhang Heng is more like a mysterious machine that imitates the operation of the universe. The Book of Jin records Zhang Heng's armillary sphere like this:
"Zhang Heng also made an elephant, with internal and external rules, the north and south poles and the yellow equator. Twenty-four gas, twenty-eight nights, Chinese and foreign officials, five latitudes of the sun and the moon, were leaked into the room on the temple. Among the stars, outside, it does not correspond to the sky. "
Guangzhou armillary sphere.
Recovery after loss
Because the drawings and records of Zhang Heng's armillary sphere have been lost, and the source of the so-called "annotation of armillary sphere" is unknown, what principle this cosmic instrument works on has become a mystery. We only know that Zhang Heng's armillary sphere is not the first one in China. It is mentioned in the Book of Jin that "the ancient elephant is divided into two parts, seven feet, three inches and a half a week." . Zhang Heng changed the system and divided it into four parts, including four feet six inches every Monday. It can be seen that Zhang Heng's armillary sphere is the result of transformation on the basis of an older prototype. The oldest armillary sphere may have only two rings: the equatorial ring fixed parallel to the equator and the polar ring (also known as the "four-row ring") that can rotate around the polar axis. Both rings are engraved with the day of the week. But on Zhang Heng's armillary sphere, besides the equator and the red pole, there are also the ecliptic, "Twenty-four Qi, Twenty-eight Nights, Chinese and foreign officials, and the five latitudes of the sun, the moon and the moon". If you want to reflect all the complicated pictures and texts, you need a huge celestial sphere-is Zhang Heng's armillary sphere a huge celestial sphere with several rings?
Later scholars have been trying to copy Zhang Heng's armillary sphere that can run by itself, but the final result is only to add one instrument after another that can't run by itself. In the Northern Wei Dynasty, Dendrobium was added to the base to correct the grade of musical instruments. In the Tang Dynasty, Li fixed the horizon, meridian and equator outside Zhang Heng's armillary sphere together, and called it the "Six-in-One Instrument", and combined the four rings that could rotate inside and the peeping tube that peeped at the stars into a "Four Patrol Instrument". Between these two layers, plus the ecliptic ring, the white ring ("white" is the orbit of the moon) and the equatorial ring, it constitutes the "three instruments." This eventually became the model of the armillary sphere we see today. Although the armillary sphere of Nanjing Purple Mountain Observatory is a disciple of Zhang Heng's armillary sphere, it is a direct biography of Li's improved armillary sphere.
Visitors who go there today can imagine that under the vast starry sky, the officials of the ancient celestial supervision department are struggling to turn those huge rings and observe the vast starry sky through peepholes.
Author Leehaeun
Editorial office
Proofread Xue Jingning