What's Visible from Outer Space

You may have heard it said that the Great Wall of China is the only man-made object visible to the naked eye from outer space. Not true. As a matter of fact, astronaut Ed Lu told Space.com recently, a great many human artifacts can be seen on earth from space — cities, airports, roads dams, ships, the Great Wall and the pyramids of egypt — and he's got digital photographs to prove it.