Fact Check: "The Great Wall of China is visible from space"
What We Know
The claim that the Great Wall of China is visible from space has been widely circulated and is often considered a myth. In October 2003, Chinese astronaut Yang Liwei stated that he could not see the Great Wall from space, which contradicted popular belief and previous assertions made in various media (López-Gil, 2010). Following this, astronaut Eugene Cernan mentioned that under certain conditions, the wall might be visible, but this was later clarified by the European Space Agency (ESA), which acknowledged that the image attributed to the Great Wall was actually of a river (López-Gil, 2010).
The Great Wall is approximately 7,300 kilometers long but less than 6 meters wide in most places, making it extremely difficult for the human eye to discern from a distance. The limitations of human visual acuity mean that even under optimal conditions, the wall would not be visible from space without the aid of high-powered lenses (López-Gil, 2010). NASA has also confirmed that the Great Wall is not visible from the moon and is challenging to see even from low Earth orbit without specialized equipment (NASA, 2009).
Analysis
The reliability of the sources discussing the visibility of the Great Wall from space is high. The article by Norberto López-Gil published in a peer-reviewed journal provides a scientific basis for understanding human visual limitations, citing various studies on visual acuity (López-Gil, 2010). NASA's statements are also credible, as they come from a leading space agency with extensive experience in space observation and imaging (NASA, 2009).
Critically, while some astronauts have claimed to see the Great Wall, these assertions have been met with skepticism due to the lack of consistent evidence and the inherent limitations of human vision. The ESA's correction regarding the misidentified image further underscores the confusion surrounding this claim (López-Gil, 2010). Additionally, other sources, such as Snopes and BBC Sky at Night Magazine, reinforce the idea that the Great Wall is not visible from space, citing similar reasoning regarding visual acuity and the wall's dimensions (Snopes, 2020; Sky at Night Magazine, 2020).
Conclusion
The claim that the Great Wall of China is visible from space is False. Scientific evidence and expert testimony indicate that the wall's narrow width and the limitations of human vision make it impossible to see from space without the aid of specialized equipment. Despite its length, the wall does not stand out against the Earth's surface, and claims to the contrary are based on misconceptions and anecdotal evidence rather than empirical data.
