China’s Great Wall not so great from space?
We’ve all heard that The Great Wall of China is the only man-made object visible from space. You may have heard it from a friend, a teacher, or even a textbook. But is it true?
Actually this is largely a great myth, as not only are many other man-made object visible from space, but the Great Wall may not be all that visible as well.
Ironically, it was a Chinese astronaut, Yang Liwei, who debunked the myth. Liwei – who was China’s first man in space – said upon his return “the scenery was very beautiful… but I didn’t see the great wall.” Unsurprisingly many people in his home country were less than impressed with his comments.
What can we see from space?
Firstly, on the moon you certainly can’t see any man-made objects. The few astronauts that have been there have said that they could see blue oceans, white clouds, yellow sand and the odd patch of vegetation.
Earth by Joseph via Flickr
If you travel only a couple hundred kilometres up into space and you can actually make out many man-made structures with the naked eye. These include bridges and high-rise buildings.
The Great Wall is very rarely one of these visible man-made objects. What makes the great wall so hard to see is not actually its size, but its colour. The Wall does not provide much contrast from the surrounding landscape, so it is very hard to make out.
Much less impressive landmarks such as desert roads are usually much easier to spot, as they provide more of a contrast to their surrounds.
So, in truth, the Great Wall has been seen from space. However, this has only been possible under the right weather and light conditions.
So where did this myth come from?
This myth dates dates back to 1932, when a Ripley’s Believe It or Not! Cartoon said that the “the [Great Wall is] mightiest work of man, the only one that would be visible to the human eye from the moon.” This belief has been perpetuated for decades so much so that pretty much everyone believes it to be the truth.
A few years later the respected adventurer Richard Halliburton made similar claims in his book, Second Book of Marvels, and the claim soon turned into fact, appearing in school textbooks. Importantly these claims were made when no one had been to space, so it was impossible to know if it was truth or not.
Backlash in China
Controversy surrounded the topic when another Chinese astronaut, Leroy Chiao took photos of China from the Internatioanl Space Station in November 2004. These photos were greeted with relief by the Chinese as many thought they proved that The Great Wall could be seen, and were displayed prominently in Chinese newspapers.
However, even the astronaut himself was unsure whether The Great Wall could actually be seen in any of his pictures.
NASA has even weighed in on the debate with NASA’s chief scientist for Earth observation, Kamlesh P. Lulla saying that The Great Wall is generally very hard to see and photograph. However, Lulla went on the acknowledge that The Great Wall was most likely visible in the photographs taken by Leroy Chiao, and that the weather conditions appeared ideal for sighting The Wall.
So, whilst under the perfect conditions the The Great Wall can be seen from space, it is definitely not the only man-made object “that would be visible to the human eye from the moon.”