This is a myth; astronauts confirm that the Wall is not visible from the Moon without aid. The Great Wall of China is often said to be the only human-made structure visible from the Moon, but this is untrue. While the Wall is long, it is also narrow and blends into the natural landscape, making it difficult to spot with the naked eye. Astronauts who have traveled to the Moon confirm that no man-made structures can be seen without the help of telescopes or cameras.
From space, astronauts can see large features like oceans, deserts, and city lights at night, but even from lower orbits around Earth, the Great Wall is not easily visible. Other human-made structures, like roads, airports, and bridges, can sometimes be seen more clearly than the Wall because of their contrast with the environment.
