PopTech : Blog : The growing woes of coral reefs

PopTech : Blog : The growing woes of coral reefs: "n 2003 Chinese astronaut Yang Liwei quietly dispatched a centuries-old myth, when he said publicly that despite his best efforts, he hadn’t been able to see the Great Wall of China from space. The ancient world’s longest construction, awesome though it is, is the same dusty color as the hills it’s made from, only nine meters wide, and time-weathered. Optometrists have argued that to see the Wall from space with the naked eye, even at low orbits, you would need 20/3 vision, 7.7 times better than ordinary human sight.
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