Artificial structures visible from space

The Kármán line, at 100 kilometres (62 mi), is accepted by the World Air Sports Federation, an international standard-setting and record-keeping body for aeronautics and astronautics, as the boundary between the Earth's atmosphere and outer space.

The claim that the Great Wall of China is the only man-made object visible from the Moon or outer space has been debunked many times, but remains a common misconception in popular culture.

[1][2][4] According to astronauts Eugene Cernan and Ed Lu, the Great Wall is visible from the lower part of low Earth orbit, but only under very favorable conditions.

[16] The human naked eye has an angular resolution of approximately 280 microradians[17] (μrad) (approx 0.016° or 1 minute of arc), and the ISS targets an altitude of 400 km.

However, since this would be at the absolute limit of the resolution, objects on the order of 100 m would appear as unidentifiable specks, if not rendered invisible due to other factors, such as atmospheric conditions or poor contrast.