NASA has revealed that the most visible human structure from space is not the famous Great Wall of China. Discover the real record-breaking construction.
The popular belief that the Great Wall of China It is the only man-made structure visible from space is a myth that has persisted for decades.
From an early age, we imagined this colossal Chinese construction winding through mountains and deserts, so grand that it could be seen by astronauts in orbit.
But the reality is different. Surprisingly, the most visible structure from space is not in Asia, but in Europe, and it's not what you'd expect: a “sea of plastic” formed by greenhouses in the Almería region of Spain.
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Is the Great Wall seen from space?
The Great Wall of China, with its more than 21 thousand kilometers in length, is undeniably an impressive work. However, several factors make it practically invisible from space:
- Narrow width: Despite its length, the wall is only 4 to 5 meters wide, a thin line that disappears into the vastness of the Earth seen from space.
- Low height: At around 6 to 7 meters high, the wall does not cast significant shadows that make it stand out from its surroundings.
- Natural camouflage: Built with local materials, the wall blends into the landscape, especially in mountainous regions.
Almería — A sea of greenhouses visible from space
While the Great Wall of China hidden from the gaze of the astronauts, the greenhouses of Almería shine brightly.
Covering around 40 thousand hectares, this vast expanse of white plastic reflects sunlight so intensely that it becomes visible to the naked eye from space.
Images from NASA and the European Copernicus program prove this phenomenon. Spanish astronaut Pedro Duque stated that, from the International Space Station (ISS), human activity is only visible “in the greenhouse field in the south of Almería“, due to the “great reflective capacity of sunlight” of the plastic covering the greenhouses.
The impact of greenhouses
The transformation of the Almería landscape is a relatively recent phenomenon. Until the 1950s, the region was arid and desert, an ideal setting for Western films.
Starting in the 1970s, NASA began recording the expansion of greenhouses, which transformed the region into a “sea of plastic”.
In addition to the visibility from space, the greenhouses of Almería can cause a local cooling effect, since the white covering reflects a significant amount of sunlight, as pointed out by NASA.
The evolution of agriculture in Almería
The history of Almería's greenhouses began with farmers who, in the 1950s and 1960s, experimented with covering the soil with sand, mulch and plastic to protect crops from sea winds.
The results were surprising: growing in greenhouses proved to be much more productive, as the soil retained more heat and moisture.
With the introduction of techniques such as drip irrigation, artificial soil use and hydroponics, agricultural production in Almería has intensified. The region, previously semi-arid and sparsely populated, has become an agricultural powerhouse, adapting natural conditions to technological innovation.
Adapting to the Climate
To control the temperature and humidity inside greenhouses, farmers developed a peculiar technique: lime bleaching.
During the summer, natural ventilation is not enough to dissipate the heat, and lime is applied over the plastic to reduce solar incidence.
In late August, the lime is removed to allow for the necessary warming for winter and spring crops.
Almeria in numbers
The economic importance of Almería's greenhouses is undeniable. Data from the Andalusian Ministry of Agriculture (2021/2022) shows that the region has 47.911 hectares of area cultivated in greenhouses, producing more than 3,4 billion kilos of fruits and vegetables, with a value of R$2,7 billion.
Most of the production (peppers, tomatoes, pumpkins, eggplants, among others) is exported to countries such as Germany, France and the United Kingdom.
Almería is not alone in this “sea of plastic”. Spain has around 70 hectares of greenhouses, making it the second country with the largest area covered in polyethylene, behind only China, with 82 hectares.
A 2023 report by the Food and Agriculture Organization of the United Nations (FAO) warns of growth overall the use of plastics in agriculture.
Demand for greenhouse cover, soil and silage is expected to increase by 50% by 2030, reaching 9,5 million tonnes.
With information from NASA.
At school, my teacher, who has already passed away, says that part of the wall was hidden.
It's incredible, every day we learn more new things, magnificent
I would like you to help, wouldn't this photo make our Earth smaller?