Thanks to Jolene at From Quarks to Quasars
It’s a myth that has persisted for years: the Great Wall of China is the only man-made object that you can see from space. Or even worse, that the Great Wall is the only feature that you can see from the Moon without assistance.
Even if you haven’t heard this myth, I’m sure you’ve often wondered what the Earth looks like from a distance. If neither of these things is true….well then, you should probably get out more.
Let’s tackle the more unbelievable statement first—seeing the Great Wall from the Moon. In fact, seeing the Great Wall from the Moon’s surface would be the same as seeing a human hair from 2 miles away (3.2 km). Unless you have a high-powered telescope, or eyesight that is out of this world,* you’re not going to be able to see such a tiny object.
Given the average distance of the Moon, some 238,000 miles from the Earth (383,000 km), a feature on our planet would have to be roughly 70 miles across (113 km) for the unaided human eye to be able to discern it from the surrounding landscape. At its widest, The Great Wall is a mere 30 feet (9.1m). So it’s not even close.
When asked what features are visible from the Moon, Apollo 12 astronaut Alan Bean stated, “The only thing you can see from the Moon is a beautiful sphere, mostly white, some blue and patches of yellow, and every once in a while some green vegetation. No man-made object is visible at this scale.”