why can the great wall of China be seen from space?

Answer 1

The Wall is included in lists of the "Seven Medieval Wonders of the World" but was of course not one of the classical Seven Wonders of the World recognized by the ancient Greeks.

The Wall was made a UNESCO World Heritage Site in 1987.
The Great Wall of China as seen in a false-color radar image from the Space Shuttle, taken in April 1994
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The Great Wall of China as seen in a false-color radar image from the Space Shuttle, taken in April 1994

Mao Zedong had a saying, 不到长城非好汉 bú dào Chángchéng fēi hǎo hàn, roughly meaning "you're not a real man if you haven't climbed the Great Wall".
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From outer space

There is a long standing disagreement about how visible the wall is from space.

Richard Halliburton's 1938 book Second Book of Marvels said the Great Wall is the only man-made object visible from the moon, and a "Ripley's Believe It or Not" cartoon from the same decade makes a similar claim. This popular belief has persisted, assuming urban legend status, sometimes even entering school textbooks. Arthur Waldron, author of the single most authoritative history of the Great Wall written in any language, has speculated that the belief about the Great Wall's visibility from outer space might go all the way back to the fascination with the "canals" some people during the late nineteenth century believed to exist on Mars (The logic was strange and simple: If Earthlings can see the Martians' canals, the Martians might be able to see the Great Wall). But in fact, the Great Wall simply cannot be seen by the unaided eye from the distance of the moon, much less that of Mars.

The distance from Earth to the moon is about a thousand times greater than the distance from the earth to a spacecraft in near-earth orbit. If the Great Wall were visible from the moon, it would be easy to see from near-earth orbit. In fact, from near-Earth orbit, it is barely visible, and only under nearly perfect conditions, and it is no more conspicuous than many other manmade objects.

One shuttle astronaut reported that "we can see things as small as airport runways [but] the Great Wall is almost invisible from only 180 miles (290 km) up." Astronaut William Pogue thought he had seen it from Skylab but discovered he was actually looking at the Grand Canal near Beijing. He spotted the Great Wall with binoculars, but said that "it wasn't visible to the unaided eye." An Apollo astronaut said no human structures were visible at a distance of a few thousand miles. U.S Senator Jake Garn claimed to be able to see the Great Wall with the naked eye from a space shuttle orbit in the early 1980s, but his claim has been disputed by several professional U.S. astronauts. Chinese astronaut Yang Liwei said he couldn't see it at all.

Veteran U.S. astronaut Gene Cernan has stated: "At Earth orbit of 160 km to 320 km high, the Great Wall of China is, indeed, visible to the naked eye." Ed Lu, Expedition 7 Science Officer aboard the International Space Station, adds that, "...it's less visible than a lot of other objects. And you have to know where to look."

Neil Armstrong also stated: "We could see continents (on Apollo 11), could see Greenland. It stands out, just like it does on the globe in your library, all white. Antarctica we couldn't see because there were clouds over Antarctica. Africa was quite visible, and we could see sun glint off a lake. It might have been Lake Chad. I'm not certain which lake it was, but we could catch that reflection, sun reflection…. But I do not believe that, at least with my eyes, there would be any man-made object that I could see. I have not yet found somebody who has told me they've seen the Wall of China from Earth orbit. I'm not going to say there aren't people, but I personally haven't talked to them. I've asked various people, particularly Shuttle guys, that have been many orbits around China in the daytime, and the ones I've talked to didn't see it. [3]

Leroy Chiao, a Chinese-American astronaut, took a photograph from the International Space Station that shows the wall. It was so indistinct that the photographer was not certain he had actually captured it. Based on the photograph, the state-run China Daily newspaper concluded that the Great Wall can be seen from space with the naked eye, under favorable viewing conditions, if one knows exactly where to look. [4]

These inconsistent results suggest the visibility of the Great Wall depends greatly on the seeing conditions, and also the direction of the light (oblique lighting increasing the angular size of the Wall through the addition of a shadow to the physical width of the Wall). Features on the moon that are dramatically visible at times can be undetectable on others, due to changes in lighting direction. The Great Wall is only a few meters wide — sized similar to highways and airport runways — and is about the same color as the soil surrounding it.

Answer 2

It's a myth that the Great Wall is the only man-made object visible from space. Google the world at night. On a clear night, even the lights of a small town are clearly visible, as are the Trans Siberian Railway, the regular gridlike pattern of the US Interstate Highway System, the floodlights of a fleet of squid boats, which are used to attract squid, the border between North and South Korea, and the ring roads around and roads converging on, Moscow, which look like a spider's web.

Answer 3

According to Shuttle astronaut Jay Apt, the Great Wall is barely discernable, if not invisible:

" We look for the Great Wall of China. Although we can see things as small as airport runways, the Great Wall seems to be made largely of materials that have the same color as the surrounding soil. Despite persistent stories that it can be seen from the moon, the Great Wall is almost invisible from only 180 miles up!"

Answer 4

The great wall cannot be seen from the space

Answer 5

it can't be seen from space with the naked eye.

Answer 6

because the opposite of small is big

Answer 7

Well now..... think about it! It goes for hundreds and hundreds of miles and its wide enough for carts to have been used on it. Think it just might show up better than some of the major rivers??????
DUH !!!!!

Answer 8

cuz its so long and big u dip

Answer 9

because it's huge.

Answer 10

because is huge!!!!