[ExI] Fermi question

[Ben Zaiboc]

Stefano Vaj <stefano.vaj at gmail.com> wrote:

> I was thinking that after all from outer space the Chinese
> Wall emains one
> of the most obvious man-made structures ...

Urban Myth alert!

The idea of the Great Wall of China being visible from space pre-dates space travel.  It was /expected/ to be visible from space, but in fact isn't.

It's too similar to its surroundings to stand out, which is why far smaller structures are visible from orbit, but the wall isn't.  Apparently, from the Moon, absolutely nothing man-made is visible on the earth.

Ben Zaiboc