The Great Wall is not visible from the Moon

The Great Wall is long but narrow, and astronauts have said it is very hard or impossible to pick out with the naked eye from orbit. It cannot be seen from the Moon.

Context

The Great Wall is very long, with total lengths of several thousand kilometers depending on how branches and different dynasties' walls are counted, but it is narrow, usually only a few meters wide. Seeing something from a great distance depends on its width and contrast with the surroundings, not just its length, and the wall is built from local stone and earth that blends into the landscape.

The Moon is about 384,000 kilometers away, so from there even entire continents appear as blurred patches. No astronaut has reported seeing the wall from the Moon, and it is generally accepted that it cannot be seen unaided from that distance. From low Earth orbit, at around 400 kilometers, the wall is extremely hard to spot with the naked eye, though astronauts have sometimes photographed it with zoom lenses under good conditions.

Claims that the wall is visible from space appeared in print well before spaceflight existed, so they could not have been based on observation. China's first astronaut, Yang Liwei, said in 2003 that he could not see it during his orbital flight, which received wide media coverage. Roads, airports, and city lights are in practice much easier to pick out from orbit than the wall.