This has been a very popular myth that you can see the Great Wall of China from space with the naked eye and that it’s the only man-made structure that you can see from space and even from the moon. The truth is that you can’t and especially not from the moon. However, there are many made-made structures that you can see from space like the Egyptian pyramids. The only way you could get a glimpse of the wall is if you had the help of radar or high powered camera. Though, even if you tried to take a picture with a powerful camera, it would still be very hard to make out the wall. Leroy Chiao, commander and NASA ISS science officer of the 10th Station crew, tried doing this with a 180mm lens and a digital camera last Nov. 24. The picture he took was the first confirmed picture of the wall. Chiao and NASA believe that they can make out some parts of the wall. In the picture, the yellow arrow points to an estimated location of 42.5N 117.4E where the wall is visible. The red arrows point to other visible sections of the wall. Still, the wall is not easily seen because of it small width from that height and because it blends in with its surroundings. Even though seeing or taking a photograph is still hard to see it in low Earth orbit, parts of the wall can be seen quite well using radar imagery (below).
Sources:
http://www.nasa.gov/vision/space/workinginspace/great_wall.html
http://www.snopes.com/science/greatwall.asp
http://www.universetoday.com/25364/can-you-see-the-great-wall-of-china-from-space/
http://www.factmonster.com/askeds/great-wall-visible-space.html
http://www.space.com/scienceastronomy/visible_from_space_031006.html
