Astronaut Michael Collins wrote that there
is a false notion that the Great Wall of China is visible from
the Moon. Collins orbited around the Moon during the Apollo 11
mission, in 1969.
Collins, Liftoff, Grove Press, New York, 1988.
Astronaut William Pogue orbited the Earth
in the Skylab space station, in 1973 to 1974. The altitude was
about 300 miles above the Earth.
Pogue wrote that he could see the Great Wall if he used binoculars.
It was not visible to the unaided eye, however.
R. Pogue, How Do You Go To the Bathroom in Space?, Tor, New
Space Shuttle Astronaut Jay Apt
reported the following:
"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!"