By taking the Beijing subway and passing through various transfers in the road network, you can reach Jianguomen Station. As soon as you come out of Exit C of Jianguomen Subway Station, you can see a high platform in Jiebi'er.

Poet Li Bai is the most intimate drinker. Even if there is no one to accompany him, he would "raise his glass to invite the bright moon and form three pairs of shadows.". At the end of this batch of "Four Poems Drinking Alone under the Moon", Li Bai said, "You must drink fine wine and ride the moon to climb the high platform.". Although there are indeed many people riding on the moon to climb this high platform in front of me, there is no Li Bai among these people. Li Bai was from the Tang Dynasty, and this high platform was built in the seventh year of the Zhengtong reign of Emperor Yingzong Zhu Qizhen of the Ming Dynasty, which is 680 years after Li Bai's death.

Why did Li Bai climb the high platform? In the Song Dynasty, Su Dongpo said, "The sky is blue and the clouds are at night. The high platform on the city is truly transcendent.". That is to say, Li Bai went up to the high platform to seek transcendence, to give a drunken punch, and to write two drunken poems. The other people who go up the stage are not going to drink, but engaging in another very romantic behavior, which is to watch the stars and "see the meteor shower falling on this Earth.".

Before this high platform of the Ming Dynasty, someone had rammed a mound of soil here in the Yuan Dynasty and then went up to see the stars at night. Among these people, there is a very famous one named Guo Shoujing, who is a legitimate astronomer. During the Eastern Han Dynasty, over a thousand years before Guo Shoujing, Zhang Heng had been studying astronomy and geography. Before Zhang Heng, it was usually a fortune teller who would look at the stars. During the Five Hu and Sixteen Kingdoms period after the Eastern Han Dynasty, watching stars had become a profession called astrologers. I saw the astrologer on the eaves of a Zhangbi ancient castle in Shanxi last time.

You see, this astrologer didn't have a high platform to climb at that time, so he had to build a ladder on the mountain wall outside his house to climb up and see the stars. The astrologer of this Zhangbi Castle has left the profession of a fortune teller, he is neither a fortune teller nor a human; It's not considered national luck either. He wants to see the direction of the stars in the sky clearly and then guide the architectural layout of the village.

During the Zhengtong period of the Ming Dynasty, Emperor Yingzong Zhu Qizhen ordered people to build the high platform we see today for experts who watched the stars. He asked experts to step onto the high platform to calculate human life and national fortune, all of which were his own; You can also do some scientific research by the way. At this point, society has already made great progress, and divination has become a peripheral theory, making it difficult to climb to the top of the world. Zhu Qizhen asked experts to give Gao Tai an academic official name. In the Yuan Dynasty before this, the rammed earth mound that Guo Shoujing climbed was called "Sitiantai". Astronomers in the Ming Dynasty were very ashamed of the name "Sitiantai". How could ordinary people manage to control the sky? It would be great if anyone could be a driver. They believed that the sky was beyond control and only observable, so they named this high platform "Observatory", which is a platform for observing celestial phenomena. The engraved stone of this "observatory" is still above the arch of the main gate, and due to its age, the red color on the characters has faded.

The earliest legitimate observer of celestial phenomena in China may be considered as King Wen of Zhou, Ji Chang. In his work "The Book of Changes", he wrote, "The celestial phenomena are seen as auspicious or inauspicious, and saints are depicted as such.". This observatory in Beijing was used until the establishment of the Nanjing Purple Mountain Observatory in 1927, and was later designated as the second batch of national key cultural relics protection units in 1982.

On the day I came to the stage, the sky was high and the clouds were clear, with few guests and the stage empty. There were no gatekeepers at each entrance, nor were there any houses with "ticket office" signs hanging. The entrance to the stage is fully open, and it is said that it has been like this since 9am, with free visits.

As I approached the door and was about to step onto the stage, I saw a big man pouncing on the steps as if digging for something.

Although I didn't think anyone was digging a corner in broad daylight, I still asked him if he was an internet celebrity trying to win the gold medal? He said no, he is here preparing to shoot the chaotic cloud crossing in the sky. He complained to me that halfway through the shoot, he didn't protect the equipment like this. As a result, an old man walked over and pressed the button on his machine, causing everything in front to go blank and the clouds in the sky to fly away. Don't mention it, some old men really have OCD and can't help but press the button when they see it. So the soldiers in the missile unit are all young people, otherwise any old soldier would come over and press any missile launch button, and the missile wouldn't fly out casually? Flying to any place, the American troops there will suffer easily?

When I climbed the high platform, I didn't see an old man, but it was a locked gatehouse.

There are also seven, seven, eight, or eight observation instruments.

These instruments were stolen by the French and German armies when the Eight Nation Alliance invaded Beijing in 1900. The French army hid several of them in the embassy in China and returned them after two years. The German army transported several other items back to China and displayed them in the new palace behind the Worry Free Palace in Potsdam. After being defeated in World War I, they were returned to China in 1921.

Take a look at the observation instrument on the stage, which is called the "Jiheng Fuchen Instrument".

Look at its exquisite copper casting.

This Ji Heng Fu Chen instrument, also known as the equatorial theodolite, was cast by imperial decree in the 19th year of the Qianlong reign of the Qing Dynasty (1754). Ji Heng comes from the Book of Documents, which states that "Xuan Ji Yu Heng was responsible for Qi Qi's seven policies.". This Jiheng Fuchen instrument is slightly more complex than a typical equatorial theodolite, with some additional components, mainly measuring the position of celestial bodies (equatorial longitude and latitude) and solar time. In ancient times, there was no atomic clock, and precise timing relied on astronomical observation. In fact, now astronomical observation time is also used as the standard, and atomic clocks also need to be calibrated with astronomical time.

This is called the ecliptic theodolite.

In the twelfth year of the Kangxi reign (1673), a decree was issued to Belgian missionary Nan Huairen to construct a building for measuring the ecliptic longitude and latitude of celestial bodies.

The following celestial instrument was also built by a group of Nan Huairen.

This celestial instrument is used to demonstrate the position of celestial bodies in the ecliptic, equator, and when observed on the ground. Nan Huairen once built several observation instruments together, and the following chronograph is also included.

A sextant, also known as a chronometer, is used to measure the angle between two stars. Although we don't know its mystery, we often see people holding such a sextant while sailing at sea in pictures. In ancient navigation, besides having a compass to guide the course, it also relied on astronomical observations for positioning.

The following is the horizon transit instrument.

This horizon telescope was also built by Nan Huairen and is used to measure the azimuth of celestial bodies. At that time, Nan Huairen made a total of six instruments, including the quadrant below.

Quadrants are used to measure the altitude angle of celestial bodies.

The following is the horizon theodolite.

This horizon theodolite was also built during the Kangxi period, in the 54th year of the Kangxi reign (1715). You see, there is no bronze coiled dragon on it, but it has a Western style. This was not built by Nan Huairen, but by a German missionary named Julian. The horizon theodolite integrates the functions of quadrant and horizon theodolite.

On the high platform, most of the observation instruments are made by foreigners; What about domestic instruments? I walked down the high platform with a question and saw ancient Chinese observation instruments in the yard. Take a look at this one below.

Linglongyi, this was created by Guo Shoujing's students in the Yuan Dynasty according to the teacher's blueprint. That metal sphere is a layer of eggshell with many small eyes on it. When a person drills into the eggshell and looks around, they can see a sky full of stars. Because those small eyes are chiseled according to regulations, the starry sky seen inside is very realistic. Across from Beijing Zoo, there is an planetarium with a projection hall. Modern astronomers project the starry sky onto the dome of the projection hall using a projector, which is even more realistic than the starry sky seen in this exquisite instrument.

There is also a celestial globe in the yard.

The earliest celestial globe in ancient China was created by astronomer Luo Xiahong during the reign of Emperor Wu of the Western Han Dynasty, and it is also the earliest celestial globe in the world. The celestial globe can be used to measure the equatorial coordinates of celestial bodies. Since Luo Xiahong invented the celestial globe, there have been many improvements by later generations. The celestial globe here is from the Ming Dynasty and has added many functions. It can also measure the ecliptic and horizon coordinates of celestial bodies. Sixty years after the celestial globe of Luoxia Hong, similar observation instruments also appeared in Greece.

There is also a Jian Yi in the yard.

Jianyi is a simplified celestial globe designed by Guo Shoujing in the Yuan Dynasty. Three hundred years after Guo Shoujing simplified the celestial globe, a simplified version of the Greek celestial globe also appeared in the West, created by a Danish person.

I can tell at a glance that the one below is for shadow measurement.

This is called a Guibiao, and the standing copper pillar is called "Gui"; The copper plate lying down is a watch. Come and admire the scale of the shadow length cast by Gui on the watch at noon, and you can know which season is currently in the four seasons.

Guibiao can be used to observe seasons, and there is also an instrument called "sundial" that reads the same as Guibiao.

Since there is a sundial for timing during the day, there should still be a moondial for timing at night, right? Don't say it, there really is, but it's not here. You can only see the sundial through the moonlit door below.

Here it is.

Surprisingly, there is also an adjutant who works as a moon dial with a star dial, because the timing of the moon dial is not very accurate, so an adjutant is needed as an assistant. During the Northern and Southern Dynasties in China, the term "star dial" was used to represent time; But it was not until the Qing Dynasty that instruments such as moon dials and star dials appeared. How do you know the time at night without a moondial or a star dial? Then we need to rely on listening to the old man playing bangzi.

There were many astronomers in ancient China, and the one we are most familiar with is Zhang Heng during the Eastern Han Dynasty.

Zhang Heng promoted the theory of the cloudy sky established by his predecessors, and also upgraded the technology of the celestial globe invented by his predecessors, installing a hydraulic transmission system. This new celestial globe is called the "Leakage Turning Celestial Sphere", which can move on its own and demonstrate celestial motion in chronological order. It is very magical.

Of course, the most familiar invention by Zhang Heng is also known as the "seismograph".

During the Zhengtong era, when building this observatory, it was necessary to build some small rooms so that the celestial officials could rest after ascending the platform in the morning and evening. That house is still there, the one from the Ming Dynasty. Because this observatory has been in use all along, the house has been continuously repaired and in good condition.

The main hall is called "Ziwei Hall". In ancient Chinese astronomy, the area around the North Star was called the Ziwei Wall, and the "Ziwei" on the plaque here should have the meaning of observing celestial phenomena. In ancient divination, there is also the saying "Zi Wei Dou Shu", which is a technique of calculating people's fortune based on the birth date and eight characters. Therefore, this observation also means guessing the royal destiny and national fortune. Haha, you see, I really got it right. These people who observe celestial phenomena really have the function of calculating royal luck.

Although this is an agency for the emperor, the house is not of high standard. Seen from the outside, it is a gable roof with five ridges of grey tiles and five rooms of width. This type of roof can be found in both the eastern and western urban areas, even in Xuanwu Chongwen. Here, the noble identity is displayed by the huge main ridge and the brick carved phoenix kisses at both ends. Upon entering the house, it was a residential building with a raised beam structure roof.

There is an exhibition of "Chinese Starry Sky" being held in this hall.

There are also some precision machines inside.

The one above is a taxi, not paid by mileage, but by how many miles you have traveled. Every mile this car goes forward, the wooden man on the car beats the drum. "Eight thousand miles of clouds and moon" means that Caiyun is riding this car chasing the moon, and the wooden man on the car beats eight thousand drums. Why not hire a living person to ride in the car and beat the drum? Who among the living can do this job? Endless drumming of 8000 beats, who can handle it? This taxi was also invented by the great Zhang Heng, earlier than Zhuge Liang's wooden ox and flowing horse.

After passing by the Jianguo Gate for so many years, I have always missed this ancient observatory. Today, on my trip, I finally saw the back of its neck and the bronze artifacts on its back. Of course, these bronze artifacts are all contemporary replicas.