This Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)
sub-image covers a 12 x 12 km (7.5 x 7.5 miles) area in Northern Shanxi Province, China, and was acquired January 9, 2001. The low sun angle,
and light snow cover highlight a section of the Great Wall, visible as a
black line running diagonally through the image from lower left to upper
right. The Great Wall is more than 2000 years old and was built over a period
of 1000 years. Stretching 7240 km (4500 miles) from Korea to the Gobi Desert, it
was first built to protect China from marauders from the north.