Recently, the Chinese space station flew over Beijing, people recorded exciting pictures with the lens in Tiananmen Square, so long ago I heard that the Great Wall can be seen from space, and the primary school Language textbook has also written in this way, so can the three astronauts of our Chinese space station really see the Great Wall from the hanging window? The answer is no, but after nearly 70 years of debate about it, the records in the book can only be beautiful imaginations? Let's find out with this article.
九年义务教育六年制小学四年级2001版语文教科书第7册20课《长城砖》一文，这样写道：
"Truly remarkable!" One astronaut said with great excitement, "I am on a spaceship, observing our planet from beyond the sky, and I can only recognize two projects with the naked eye: one is the Holland sea levee, and the other is the Great Wall of China!" ”
So we clearly remember this knowledge point, in 2000, the Chinese high school exam paper reading comprehension of the "Great Wall" article stated:
"The only artificial trace on Earth that can be seen in outer space is you, the Great Wall!"
Over the years, "can we see the Great Wall from space just by the naked eye" has become one of the driving forces for us to explore space. Before Chinese went to space, there were many opinions, in fact, it could be calculated theoretically, but everyone was still unwilling to destroy this beautiful vision.
Such a statement is also very popular in foreign countries, and the knowledge card attached to a cereal in the United States is printed with the words "Do you know that the Great Wall of China is the only man-made object visible to the naked eye in space?" Some places even say that "the only man-made object on the moon that is visible to the naked eye is the Great Wall." Such a statement is not empty.
In fact, from the "space to see the Great Wall", the earliest is an American entertainment company called "Believe It or Not", which declared in 1932: Looking at the earth on the moon, the Great Wall is the only human building that can be seen. It's not that the entertainment company is talking nonsense, they also found this conclusion in the literature.
In 1754, a British paleontologist wrote in a letter: "The length of the Great Wall of China is a considerable number on the surface of the earth, and it may be visible from the moon..." In fact, it was 215 years before humans landed on the moon. In 1895 the English writer Henry Norman inherited one of the claims in his book, which was mentioned for the first time in a formal publication, and Europeans were quick to believe it.
In the 1930s, the myth spread to China, and on March 3, 1931, the Beiping Morning Post published the "Complete Compilation of Hu Shi's Diary":
"Brother also saw a Book in France that said that if people can go into the moon and look down on the buildings on the earth, there is only the Great Wall, which also shows the cultural spirit of our nation, Qin Shi Huang."
This is actually a quote from a series of prints in the 1932 series of "Believe It or Not" produced by the American actor and writer Robert Ripley.
In 1969, NASA used Apollo 11 to send three astronauts to the moon, and Armstrong, the first person to land on the moon, was later asked more than once: Did you see the Great Wall on the moon? He also explained time and again that it was impossible to see any artificial structure on Earth on Earth with the naked eye on the moon. This answer, while disappointing, is true.
The moon is 380,000 kilometers away from the earth, the width of the Great Wall is less than 10 meters, if the scale is equal, the Great Wall is only 80 microns wide, less than the width of a hair, not to mention the atmosphere, there are clouds, light and other barriers.
When the Apollo 11 spacecraft took a picture of the earth rising on the lunar horizon came out, we could clearly see the blue planet, and the myth of seeing the earth's artificial objects with the naked eye was self-evident, from which it could be concluded that the naked eye could not see the Great Wall from the moon!
Although this is well understood, in 1987, unesco inscribed the Great Wall on the World Heritage List, as described in the official documents:
"The Ming Great Wall is an absolute masterpiece, not only because of the military strategic ideas it embodies, but also as a perfect architecture. As the only man-made structure seen from the moon, the Great Wall is spread over a vast continent and is a perfect example of architecture blending into the landscape. ”
Once again, this claim is firmly believed.
Perhaps, the Great Wall cannot be seen from the moon, so can it be seen from the space station 400 kilometers above the ground? American astronaut William Pogue, who also studied this issue at the Space Laboratory on the International Space Station from 1973 to 1974, mentioned in his book "How to Wash in Space": "At an altitude of about 300 miles, the Great Wall cannot be seen with the naked eye, but with the help of a telescope." ”
There are three main reasons for not seeing: First, is the porthole of the space station facing the ground? Second, is it daylight when the space station passes over the Great Wall, with plenty of sunlight? The third is: can the naked eye find the Wall of the Great Wall of almost the same color from the lofty mountains at this height?
American astronaut Jay Apt took the initiative to look for the Great Wall, in fact, this height has been able to see many artificial buildings with the naked eye, but the material of the Great Wall is similar to the surrounding landform, it is difficult to distinguish, he pointed out that 180 miles (289.68192 km) height is impossible to see the Great Wall. Ed Lu, a Chinese-American astronaut, said that even if you look at the Great Wall from a slightly lower aviation plane, it is more demanding than other artificial buildings, which require very harsh conditions such as light and direction.
In 2000, Phoenix TV interviewed Aldrin, one of the first astronauts to land on the moon. He said: "There is no irregular Great Wall on the moon, and it is difficult to see irregular things in orbit.
In the same year, tito, the first space tourist, also said in an interview with reporters that when I flew over China, I saw China's rivers and mountains, but I did not see the Great Wall of China.
Although the answer is understood, this rumor still appears in the textbooks, and some expert professors suggest that the textbooks be revised. When American astronaut Eugene Andrew Cernan (1934-2017) visited Singapore in February 2004, he said with great certainty: "In low-Earth orbit at an altitude of 160-320 kilometers, the Great Wall can be seen with the naked eye." ”
As if it had been negotiated, on 11 May 2004, ESA released a high-resolution satellite image obtained by the Proba satellite during its transit on March 25 under the title "The Great Wall of China from Space" on the front page of the website, and the text description pointed out that a thin and winding line in the upper right of the map was the Great Wall that extended 7240 kilometers. The announcement also believes that if the weather, light and other conditions are suitable, astronauts can see the Great Wall with the naked eye.
The day after the announcement was released, NASA also forwarded the news, and the news of these two international authoritative institutions immediately attracted widespread attention, similar to the report that "seeing the Great Wall from space is not a myth" appeared in many domestic media, and there was an article "stopping" the proposal of cppcc members to suggest that primary school language classes should be corrected. In the same month, during a visit to China, former Soviet female cosmonaut Tereshkova revealed that she had seen the Great Wall during the 48-circle orbit around the earth in 1963.
But soon, researchers at Fudan University and the University of California pointed out that according to the three-dimensional effect and flipping 180 degrees, this cannot be the Great Wall, and the image is obviously a ravine where water flows converge.
Eight days later, ESA issued a correction announcement acknowledging that the previous image was incorrectly labeled, and they misjudged the river flowing into the Miyun Reservoir as the Great Wall. For the sake of prudence, on May 27, 2004, Beijing Municipality organized relevant surveying and mapping researchers to once again analyze the ESA images, and after aerial photography and 1:1 terrain superposition comparison, put forward a new view: the Great Wall and the river are incorrect, and it is a mountain road.
ESA made 2 mistakes, which became a joke for a while. Yang Liwei, China's first astronaut to enter space, also confirmed in a program hosted by Sabine: "It is very beautiful to see the scenery of the earth, but I did not see our Great Wall." ”
But some people have proposed it: In the 21 hours of spaceflight, Yang Liwei did not fly over the Great Wall during the day, and his failure to see it does not mean that he cannot see the Great Wall from the naked eye of space!
On October 12, 2005, Fei Junlong and Nie Haisheng flew in space on Shenzhou 6 for five days, and were also asked whether they had seen the Great Wall, so that astronauts on every Shenzhou spacecraft mission were asked about this question. The answer is the same: no! Yang Liwei even said: "When Shenzhou 5 rises to an altitude of more than 30 kilometers from the ground, the Great Wall can no longer be seen! ”
Since then, Professor Dai Changda, "one of the pioneers of China's remote sensing industry," pointed out:
"On the issue of looking at the Great Wall with the naked eye, foreign voices dominate, and many domestic academics, non-governmental organizations, and the media are following behind and shouting, without seriously making scientific arguments about it." Chinese scientists should have the responsibility to carry out some work within their capabilities and make their own scientific voices heard in the international community. ”
In the following two years, the scientific community has repeatedly analyzed the controversy of "seeing the Great Wall from space" in academic journals, some of which are explained from the structure of the eye, and some are analyzed from the optical aspect. The final conclusion: the Great Wall cannot be seen by the naked eye in space!
The topic was ignited again two years later, and on September 17, 2018, Russian cosmonaut Oleg Artemyev and German cosmonaut Alexander Gerst announced that after years of searching, they had finally taken a picture of the Great Wall on the International Space Station with a high-resolution camera.
Since the Great Wall cannot be seen with the naked eye, it is understandable to use instruments and equipment to watch on the space station. But even this condition is harsh: angle, light, resolution. With the continuous development of China's manned space industry, this controversy has become a final decision, and Chinese has clearly ended the rumors with personal experience.
When the Chinese space station was built, everyone was also full of expectations, because the Chinese Tiangong was about 380 kilometers from the ground, and it could circle the earth every 90 minutes, passing through China 16 times a day, and if you use a specific telescope or other instrument, you can completely see the Great Wall. It's just that this is the work that China's high-score satellites have to do, and there is no need for the space station to do it. Friends who are interested in seeing the ground in space can see the Great Wall and even pedestrians on the ground through high-score satellites such as Jilin No. 4.
Of course, there is another way: First, put lights on the Great Wall so that astronauts can see it at night. Netizens joke that "putting tiles on the Great Wall" is not a good idea, it is a way to use light to expand the observation target.
With our astronauts on duty in space, controversies and rumors such as these have been reduced. But as photos of The Passage of the Chinese Space Station continue to circulate online, a new question arises: Why can we see the Chinese Space Station with the naked eye?
In fact, this question is very easy to answer: because the surface of the Chinese space station can reflect the light in the universe, making it like a star moving around the earth, because of its large size, counting the length of the solar sail board is about 30 meters, the brightness can reach -1 magnitude, which belongs to the visual magnitude, of course, can be seen.
Looking back at this "Great Wall from space" debate, it is not difficult to find a law that when you are not capable of exploration and research, all conclusions can only be regarded as truth. When we travel through space, rumors that are beautiful and unscientific will naturally shatter, and this may be the great significance of our continuous achievements in manned spaceflight: to let science and truth appear in practice and exploration. #谣零零计划 #