The Chinese authorities have moved swiftly (http://uk.news.yahoo.com/040315/323/eoje8.html) to airbrush from history the popular myth that the Great Wall is visible from space.

Schools textbooks face immediate revision after the country's first astronaut confirmed that - after 21 hours in orbit - he had been unable to spot the monumental structure.

"The scenery was very beautiful," said Yang Liwei. "But I didn't see the Great Wall."

This is not the end of the matter. US astronaut Gene Cernan is quoted in the Singapore's Straits Times (http://straitstimes.asia1.com.sg/news/story/0,4386,240173,00.html) as saying that "At Earth orbit of 160km to 320km high, the Great Wall of China is indeed visible to the naked eye".

Cernan reckons Yang simply wasn't trying. He said: "If you know where to look and you look hard enough, you can also see the Astrodome in Houston, Texas, where I live."

Incredible. You didn't spot any WMDs while you were up there, did you, Gene? ®