“You can see the Great Wall,” confirms astronaut Ed Lu, who was the science officer of Expedition Seven on the International Space Station. The station circles Earth higher than Yang Liwei’s orbit.
Link to Cecil’s Column: Is the Great Wall of China the only manmade object you can see from space?
Come 1st January, I wonder if they’ll be able to see the march in Hong Kong.
Link? One suspects a certain amount of wishful thinking.
Welcome to the Straight Dope Message Boards, Raiden, we’re glad to have you with us. When you start a thread, it’s helpful to others if you provide a link to the column you’re discussing. No biggie, I’ve edited one in for you, and you’ll know for next time. Again, welcome!
Cecil’s column didn’t claim that one can’t see the Great Wall from orbit, but only that (a) it’s not the only man-made structure that you can see from space, and that (b) you can’t see it from the Moon.
It’s seems somewhat unlikely one can see TGWOC or a road from earth orbit. Think of the last time you looked down from an airplane at typical jet cruising altitude, 30,000 feet. You could probably make out roads quite easily if you have fair or better eyesight.
Now imagine you were SIXTEEN times higher. Everything would look sixteen times smaller. Probably pushing the limits of human eyesight to see something that narrow.
Cecil’s comments about Gemini photos showing the launch pad are not terribly germane-- we don’t know what kind of lens was on the camera. If it had a telephoto lens, that would make the pictures not comparable to human eyesight.
Much more about Ed Lu from a previous thread