The Great Wall of China
The Great Wall of China is one of the greatest wonders of the world. It was listed as a World Heritage by UNESCO in 1987. It is very beautiful and enigmatic. The Wall we see today was mostly built during the Ming Dynasty (1368 - 1644).
The Great Wall is one of the largest building construction projects ever completed. It stretches across the mountains of northern China, winding north and northwest of Beijing. It is constructed of masonry, rocks and packed-earth. It has over 5,000 km (=10,000 Li) long. Its thickness range from about 4.5 to 9 meters (15 to 30 feet) and goes up to 7.5 meters (25 feet) tall.
Can the Great Wall of China be seen from the moon or outer space?
Many are familiar with the claim that the Great Wall of China is the only man-made object visible from space or from the moon with the naked eye. This is simply not true.
From a low orbit of the earth, many artificial objects are visible on the earth, such as highways, ships in the sea, railroads, cities, fields of crops, and even some individual buildings. While at a low orbit, the Great Wall of China can be seen from space but it is not unique in that regard.
Furthermore, when leaving the earth's orbit and acquiring an altitude of more than a few thousand miles, no man-made objects are visible at all. NASA says, "The Great Wall can barely be seen from the Shuttle, so it would not be possible to see it from the Moon with the naked eye."
Beyond the walls, in a dominant position on the land, the wall further comprises elements such as gates, watchtowers and forts.
by Fabiano Motta – 6th level – Profª Nayla