The Great Wall of China

Although we won't be studying the Great Wall of China in our China unit, many students have expressed interest in the subject. I thought it would be a good idea to post some information on the subject.

Great Wall FAQs

Visibility from low earth orbit

A more controversial question is whether the Wall is visible from low earth orbit, i.e., an altitude of as little as 100 miles (160 km). NASA claims that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other man-made objects. Other authors have argued that due to limitations of the optics of the eye and the spacing of photoreceptors on the retina, it is impossible to see the wall with the naked eye, even from low orbit, and would require visual acuity of 20/3 (7.7 times better than normal).

"Great Wall of China -." Wikipedia, the free encyclopedia. Web. 03 Dec. 2009. .