The Debunker: Can You See the Great Wall of China from the Moon?

by Ken Jennings

In honor of the late Neil Armstrong and the Apollo astronauts, we’ve asked Jeopardy! champ Ken Jennings to run down some common misconceptions that lots of people still believe about the moon. Did you know it’s not even made out of green cheese? Science ruins everything.

Moon Myth #4: The Great Wall of China Is the Only Manmade Object Visible from the Moon.

This myth was always slightly silly. From the surface of the Moon, the Earth only looks about four times bigger than a full moon does to us, so that’s about the size of a jam jar lid held at arm’s length. The lunar explorers of the Apollo era described the Earth at that size as a brightly lit swirl of blue and white and brown—they had a tough time making out continents, much less a brown line only 30 feet wide. That would be like claiming to see a human hair from two miles away.

This oft-repeated factoid is probably a corruption of a slightly different claim, that the Great Wall is the only manmade object visible “from space.” (This is how the question was phrased in the original 1984 version of Trivial Pursuit, for example.) If we take “from space” to mean “low earth orbit,” it’s still not really true. For one thing, the Great Wall of China is still very hard to see, if not completely invisible, from one hundred miles up. Yang Liwei, China’s first “taikonaut,” tried to spot the wall in 2003 but reported he was unable to. In 2005, however, a Chinese-American astronaut aboard the International Space Station, Leroy Chiao, was able to photograph the Great Wall with a digital camera, but the object was so fuzzy he wasn’t even sure what he was seeing.

Even if we concede that the Great Wall might be barely visible to the naked eye, under perfect conditions and to someone who knows where to look, it’s not the only such manmade object. Since the Mercury days, astronauts have reported seeing cities, bridges, highways, dams, and even the Kennedy Space Center itself from space. In 1963, astronaut Gordon Cooper surprised NASA by reporting that he could see individual trucks and buildings from orbit, if there was enough contrast between them and their surroundings. The Great Wall may be 13,000 miles long, but it’s comparatively narrow and about the same color as the land around it. So next time you’re in orbit, remember to look around. You have plenty of other choices if you’re not in the mood for Chinese.

Quick Quiz: The majority of today’s Great Wall was built during which Chinese dynasty, also known for its porcelain?

Ken Jennings is the author of Brainiac, Ken Jennings's Trivia Almanac, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.

Photo by Flickr member eviltomthai. Used under a Creative Commons License.