The Great Wall of China made news earlier this month when scholars announced that, first, the Great Wall is actually Great Walls and, second, that the Great Walls are twice as long as originally thought.
The Great Wall was originally commissioned by the first historical emperor of China, Qin Shi Huang, at the dawn of the Zhao Dynasty between 220 and 206 BC. However, the contemporary Great Wall is actually a series of fortifications built, rebuilt, connected, and extended over the course of 13 dynasties, and when all those walls are taken together, they stretch over 13,000 miles — more than twice the length most list for the Great Wall of China today.
This sheer scale has led to the urban myth that the Great Wall of China is the only man-made structure visible from space. “Visible” and “space” are pretty fluid terms but, suffice it to say, almost no human being could spot the wall with the naked eye from even the lowest of low Earth orbits. That isn’t because the Great Wall is too small, but because it’s composed of the same clay as the ground it sits on, meaning there isn’t enough contrast for the human eye to discern the Wall.
Much shorter airport runways and roads are visible from space, particularly those that run through deserts, simply because of the contrasting hue of grey-black concrete against yellow sand.
Great Wall enthusiasts insist that, in very low orbits in perfect weather conditions at dusk or dawn when shadows are longest, the Wall is visible from space — making it the only man-made political border visible from space (as it was designed to demarcate and defend the border of historical China). That’s stretching the definition of “visible” and violating the definition of “only,” as another man-made border is consistently visible from space.
WHAT IS THE ONLY MAN-MADE POLITICAL BORDER CONSISTENTLY VISIBLE FROM SPACE?
Thanks in no small part to modern technology and paranoia, the border between India and Pakistan is visible every night from Earth orbit. In an effort to curb illegal border crossings, India erected in 2003 an unbroken, overlapping series of floodlights along the entire length of its shared border with Pakistan. This border is distinctly visible to the naked eye from orbit, both for its scale and its amber hue.
Twitter-savvy astronaut Ron Garan (@astro_ron) snapped a picture of the illuminated India-Pakistan border from the International Space Station on Aug. 17, 2011. He took a follow-up shot on Aug. 21 which shows — despite competing nighttime illumination from Islamabad and New Delhi — the India-Pakistan border is distinctly visible from space at night.
Now, the India-Pakistan border is a mere 1,800 miles, well short of even the most conservative length estimates of the Great Wall of China. Whether a string of lights proves more effective at controlling a border than a series of clay fortifications remains to be seen, but India’s barricade has one distinct advantage over China’s famous Wall — it’s shiny enough to be indisputably seen from outer space.
That’s not just a definitively dazzling demarcation; it’s a fascinatingly fortified fixture of Geek Trivia.