It’s not China’s Great Wall
Nearly everyone has had a teacher, friend or local know-it-all insist that the Great Wall of China is the only man-made structure visit from outer space. Not true. Many other products of our industry (including pollution) are visible from beyond our atmosphere. Of course, you get out far enough, say, to the Moon, and you can’t see much of anything beyond clouds, water and landmass. Here’s a list of what we can see from space (without a telescope, that is):
The Great Wall—actually, this 4,500 long structure is only visible during perfect weather conditions, and only parts of restored sections near Beijing are visible from 100 miles up. Even then, since the wall is made from surrounding rock, it blends in very easily. And from the Moon? Forget it. Write off another urban myth.
Desert roads—distinctive streaks of asphalt that contrast with surrounding sand and rock, these are actually more visible than the Great Wall. Astronauts have also reported seeing airport runways, dams and canals from the windows of their spacecrafts.
The “People’s House” in Bucharest, Romania—the world’s second-largest building (and the world’s largest civilian structure) that houses the Romanian Parliament, is 340,000 square meters (3,700,000 square feet) in area, which enhances its ability to be seen from up high.
The Pentagon—At 600,000 square meters (6,500,000 sq ft) and headquarters of the U.S. Department of Defense, the world’s largest building is also visible to astronauts.
Pollution—even if the Great Wall were visible, it is now obscured by air pollution that plagues larger cities in China. Algal blooms and sewage discharge also have been photographed from outside the atmosphere. In addition, astronauts at the International Space Station took pictures of the 2012-2013 brush fires in Australia.
Deepwater Horizon oil explosion and spill—this 2010 disaster in the U.S. Gulf of Mexico was visible by NASA satellites (pictured).
Of course, high-resolution telescopes perched on circulating satellites can get a shot of just about anything. How much? Since much of that technology is still classified, not too many people are talking.
Sources: Scientific American, Discover, Wikipedia, NASA