Wall? What Wall?

Odd that years after U.S. astronauts said the Great Wall of China was the only man-made object visible from space, China's first astronaut Yang Liwei says he didn't see the wall.

Comments

[jarith]

Anyone remember an actual astronaut saying that? When you think about it, the rumor makes no sense. The wall is maybe 50ft wide, of course you can't see it from space.

[chthus]

I also always thought that was a myth, though I'm not sure that no astronaut said it. Several US interstates rival the wall for width and length, and i doubt they are seen. If anything manmade can be seen, it would have to be wide and long, height wouldn't matter. Airports or huge areas of sprawl would seem the most likely, and I'm not sure even they would make the cut.

[Windminstrel]

Snopes has an article debunking the great wall myth at http://www.snopes.com/science/greatwal.htm

[Anonymous]

howsabout that light on the Luxor in Vegas? Or any city lights for that matter. Those are manmade

[PLC]

You can see lots of stuff from space, including the Great Wall of China.

"You can see an awful lot from space," says astronaut Ed Lu, the science officer of Expedition Seven aboard the (International Space) station. "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."

"With binoculars you can see an awful lot of things," Lu wrote via e-mail in fielding a question from an Earthbound space fan. "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."

http://www.space.com/scienceastronomy/visible_from_space_031006.html

[Mark A.]

Clearly, it depends on how far up you are -- there's space, and then there's SPACE. If my back-of-the-envelope type calculation is correct, a fifty-foot wide wall would subtend an angle of ~19.5 seconds of arc at a LEO height of 100 miles. Anybody know how high the Chinese spaceshot went?

19.5 seconds is pretty damned small, but maybe not invisible. The Moon has an apparent width of about 30 minutes, which is about 90 times larger. Of course, the Great Wall is nowhere near as bright, and it would have been on the dark side of the Earth for about half his flight duration, and he was moving FAST. He was alone and thus solely responsible for everything happening in the cabin (therefore perhaps distracted). In short, because he didn't see it doesn't mean it can't be seen.

This in no way proves that it can be seen, however.

[Jack]

Incidentally, the pedant in me feels the need to point out that the article is incorrect about the Great Wall of China being one of the Seven Wonders of the World. (Unless you're talking about Sid Meier's "Civilization", of course.) See the traditional list here: http://ce.eng.usf.edu/pharos/wonders/list.html

[Jean Bart]

You can city lights from space, and those sure as hell are man-made. *duh*

[Gomer]

But Jodie Foster was able to see lotsa lights, and roads, and all that, on Vega.

[Mark A.]

JB,

As I said, there is space, and there is SPACE. Things that are quite readily visible from 100 miles (~160 km) could be all but invisible from ~250,000 miles (384,000 km). I understand that the Apollo astronauts could not see cities from the surface of the Moon (they could see a low wattage laser in Arizona, however, but this is another matter).

[nm156]

Jeff, get with the program: The headline should have been an allusion to "The Wall, pt.2"

[Alegant Marci]

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