With regard to the above node by
Orange Julius (that the Great Wall isn't particularly
discernible from
space), there is
additional information as to the
visibility of the Great Wall from space.
An American
astronaut, Gene Cernan, told the Straits Times (a
reputable daily
newspaper; THE newspaper in
Singapore) that he saw the Great Wall from outer space with his own eyes. He was giving an
interview in Singapore, when he attended the
Asian Aerospace 2004, a biannual airshow.
Eugene A. Cernan served aboard
Gemini IX (June 3-6, 1966),
Apollo 10 (May 18-26, 1969) and Apollo 17 (December 6-19, 1972). During his first space mission, he became the second American to walk in space. He was also
slated in backup positions for Gemini 12, Apollo 7 and Apollo 14. Having spent a
precise 556 hours and 15 minutes in space, out of which more than 73 hours was spent on the
Moon, he is uniquely
qualified to speak on this subject.
His exact quote was: 'At Earth
orbit of 160km to 320km high, the Great Wall of China is indeed visible to the
naked eye.' He also confirmed that it was not
observable from the moon; however, only continents and oceans are
perceivable across that distance.
The skill involved with
sighting the Great Wall, apparently, lies in
knowing where to look and
eyeballing it hard enough. From this we can
deduce that the Great Wall is not easily
noticeable from space. Depending on your
knowledge of
geography, your
perseverance, how
good your
eyesight is and the
weather conditions, you might (or might not) be able to see the Great Wall.
Therefore, when other
space cadets such as the newbie
Chinese astronaut Colonel
Yang Liwei said that the thin,
undulating structure could not be
viewed from space, he probably lacked one or more of the
factors listed above. (I stand corrected: I found out that he orbited at about 350 kilometers from Earth; perhaps he was too far away to be able to see the Wall.)
Although the
notion that the Great Wall was easily
discernible in space was blasted as an
urban legend,
NASA's position that it could not be
perceived due to its narrow
width and its earth-like
colouration also needs
revision.
Incidentally, the fact that the Great Wall is
perceptible from outer space is about to be
struck from Chinese textbooks in mainland
China because of Col. Yang's report.
Sources:
The Straits Times Interactive - http://straitstimes.asia1.com.sg/
You can view the Straits Times article "You can see the Great Wall from space" online at http://straitstimes.asia1.com.sg/news/story/0,4386,240173,00.html? from 14th March 2004 to 17th March 2004, only, after which it will be archived and inaccessible except for a fee.
Biographical Data of Eugene A. Cernan - http://www.jsc.nasa.gov/Bios/htmlbios/cernan-ea.html
Orbit details of Chinese manned space mission: "Report: Manned space mission to orbit earth 14 times" - http://www1.chinadaily.com.cn/en/doc/2003-10/09/content_270451.htm
An Associated Press report:
"China to Correct Great-Wall-In-Space Myth" -
http://www.newsday.com/news/nationworld/world/wire/sns-ap-china-great-wall-myth,0,6755225.story?coll=sns-ap-world-headlines