FactSentinel

Verdict: False.

The claim is too broad and is usually wrong when it means "visible from orbit with the unaided eye." The Great Wall is very long, but human vision from low Earth orbit depends on width, contrast, lighting, weather, and viewing angle. Much of the Wall is narrow, built from earth-toned material, and follows the surrounding terrain, so it does not stand out sharply against the landscape.

NASA's history office and astronaut accounts have repeatedly treated this as a myth. Astronauts have reported that some cities, roads, airports, dams, and agricultural patterns can be easier to see from orbit because they are wider or have stronger contrast. The Great Wall can appear in some space photographs when cameras use magnification, favorable lighting, or post-processing, but that is different from a person seeing it clearly with the naked eye.

This page addresses unaided human visibility from space. It does not claim that satellite cameras cannot photograph the Great Wall. Satellites and telephoto lenses can capture many narrow structures that the unaided eye cannot resolve.

Sources reviewed:
NASA History Office: https://www.nasa.gov/wp-content/uploads/static/history/PDFs/great_wall_less_great_from_space.pdf
NASA Earth Observatory: https://earthobservatory.nasa.gov/images/47638/the-great-wall-of-china
Encyclopaedia Britannica: https://www.britannica.com/topic/Great-Wall-of-China