It is a longstanding myth that the only manmade object visible from space is the Great Wall of China. In reality, many human constructs can be seen from space.

Shuttle astronauts can see highways, airports, dams and even large vehicles from their 135 mile high perch. Cities are clearly distinct from the surrounding countryside (Manhattan). The same is true from the higher orbit of the International Space Station, 250 miles.

"You can see an awful lot from space," says astronaut Ed Lu, science officer of Expedition 7 aboard the ISS. "You can see the pyramids from space, especially with a pair of binoculars. They are a little difficult to pick out with just your eyes. You can see roads. You can see harbors. You can even see ships; very large tankers on the ocean we can see using the binoculars."

The Egyptian pyramids have been photographed from space several times with standard digital cameras and high-powered lenses. The largest pyramid at Giza, on the outskirts of Cairo, is 745 feet wide by 449 feet high.

There are surprises, too. "You can see airplane contrails, and occasionally at the end of an airplane contrail, you will see a glint of sunlight off the airplane," says Lu. "And very occasionally, you do see other satellites go by. It is kind of a neat thing to see."

"You can see the Great Wall," Lu says. "But it's less visible than a lot of other objects. And you have to know where to look." In fact stretches of the wall aren't even visible from China. They've been buried by sand for centuries. NASA has used space-based radar to map out hidden parts of the ancient structure.

There are, of course, places in space from which you can't see how man has sculpted the Earth. Apollo astronauts could not make out manmade features from the Moon. From Mars, Earth would appear as nothing but a 'bright' star to the naked eye in the night sky.

Source: Robert Roy Britt, Space.com, 06 - October - 2003