-- THE GREAT WALL OF CHINA FROM MOON --
The Great Wall is a symbol of Chinese culture and
civilization which has stood for more than 2,000 years.
The wall is so large that it is one of only two man-made objects
which astronauts can see from space without using a telescope.
These
radar images show two segments of the Great Wall of China in
a desert region of north-central China, about 700 kilometers (434
miles) west of Beijing. The wall appears as a thin orange band,
running from the top to the bottom of the of this image. These
segments of the Great Wall were constructed in the 15th century,
during the Ming Dynasty. The wall is between 5 and 8 meters high
(16 to 26 feet) in these areas. The entire wall is about 3,000 kilometers
(1,864 miles) long and about 150 kilometers (93 miles) of the wall
appear in this image. The wall is easily detected from space
by radar because its steep, smooth sides provide a prominent surface
for reflection of the radar beam.
-- The Great Wall from space --
These radar images from space show a segment of
the Great Wall of China in a desert region of north-central China,
about 434 miles west of Beijing. The wall is the thin orange
band, running from the top to the bottom of the color image on the
left. The black and white images on the right correspond to the
area outlined by the box and represent the four radar channels of
the Spaceborne Imaging Radar. Each channel is sensitive to different
aspects of the terrain, including two generations of the Great Wall.
The continuous line is the wall built during the Ming dynasty; to
its right is a broken line showing the remains of an earlier wall
erected about 1,500 years ago
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