The idea that the Great Wall of China can be seen from space has been around since at least 1938 and is still popular today. It certainly seems plausible that such a large, linear structure would stand out from the surrounding landscape, but it’s actually not true.
Alan Bean, the fourth man to walk on the moon, said in 1969
“The only thing you can see from the moon is a beautiful sphere, mostly white, some blue and patches of yellow, and every once in a while some green vegetation. No man-made object is visible at this scale.”
But if you can’t see the Wall from the moon, how about somewhere closer to Earth? The International Space Station (ISS) maintains a low earth orbit of between 330-435 km above our planet’s surface.
The astronauts who live on the ISS have reported that man-made structures like cities are visible with the unaided eye, especially when lit at night, but that the Great Wall is not. This may well be because the materials the Wall is built from are almost indistinguishable in colour and texture from the surrounding land.
Canadian astronaut Chris Hadfield reported in 2013
“The Great Wall of China is not visible from orbit with the naked eye…It’s too narrow, and it follows the natural contours and colours [of the landscape].”
Even with modern technology the Wall is hard to spot from low earth orbit. The image of Central Mongolia above is the first confirmed shot of the Great Wall from the ISS, taken in November 2004 by US astronaut Leroy Chiao. The yellow arrow points to an estimated location of 42.5N 117.4E where the wall is visible. The red arrows point to some other visible sections of the wall. (Photo credit: NASA).
Sam blogs about all kinds of science at www.samanthagouldson.com.