Can one see the Great Wall from outer space? China's first astronaut Yang Liwei answered 'no', but an elementary school text titled The Great Wall's Bricks says astronauts can see it with the naked eye.
The text reads that an astronaut once claimed, "From my spaceship, I could identify two objects, Holland's Reclamation Dike and the Great Wall of China."
However, on a TV interview last year, Chinese space hero Yang Liwei said he couldn't see the Great Wall on our beautiful earth.
It's all a matter of optics, concerning distance and the amplitude of visible light.
Physicists say objects on the ground with a width and length of at least 500 meters can be seen from a maximum height of 300 kilometers. The Great Wall, which is only ten meters wide, will vanish at a height of just 36 kilometers.
The Chinese Ministry of Education has started to correct the fault and cancel the text. The Shanghai education department rules that all local elementary schools will use a new text book without The Great Wall's Bricks.
(CRI.com March 13, 2004)
