出典:Wikipedia
出典:『Wikipedia』 (2011/07/05 17:34 UTC 版)
The Richat Structure, also known as the Eye of the Sahara, is a prominent circular feature in the Sahara desert of Mauritania near Ouadane. It has attracted attention since the earliest space missions because it forms a conspicuous bull's-eye in the otherwise rather featureless expanse of desert. The structure, which has a diameter of approximately 50 kilometres (31 mi) and is located 400–450 metres (1,310–1,480 ft) above sea level, has become a landmark for space shuttle crews.