During World Space Week(October 4～10)，you may learn about some of the space's myths. One is: “The Great Wall of China is the only manmade object1from space with the naked eye.”
You might be2of this claim, but it's not true. In fact, astronauts say that the Great Wall is just one of many manmade3can be seen from space. From an orbit 217 kilometres4the earth，it is5to see highways，airports，bridges, dams and even large6.
Cities can even be seen clearly from the International Space Station ( ISS, 国际空间站)，7circles about 400 kilometres above the planet. “You can see the8pyramids from space with a pair of binoculars(双筒望远镜). They are a little difficult to9with just your eyes，” said Ed Lu, a US astronaut10the ISS.
“With binoculars you can also see roads, harbours and even very large11in the ocean. From the moon, astronauts cannot12any manmade features on earth and the continents are very hard13. On Mars，the earth would appear to the naked eye as14but a bright 'star'. ”15what about the Great Wall? “You can see the Great Wall from space，”Lu said. “But it's a lot16than a lot of other objects. You can only see it in radar images，17in ordinary photographs.”
No one knows who18the Great Wall story. The earliest reference to it comes in a book by a US writer Richard Halliburton，published in 1938. He wrote，“Astronomers say that the Great Wall is the only manmade thing on our planet visible to the human eye from the moon.”
Halliburton's books19quite well during the first half of the 20th century. So，if he didn't20the story himself，he certainly spread it widely.
