Can the Great Wall of China really be seen from space? That notion persists in popular lore, but it isn’t true. Despite its incredible length of at least 21,000 kilometers when counting all branches, the wall is narrow and blends into the rugged landscapes it traverses. Any human-made structure tends to disappear at the scale of space, making the claim hard to verify with the naked eye from orbit.
The most conspicuous artificial feature seen from Earth’s orbit is not in Asia but in southern Spain. The Almería region, around the town of El Ejido, contains a vast concentration of plastic-covered greenhouses. This sea of greenhouses stands out from space because of its bright, uniform color and sheer spatial extent, making it the clearest man-made formation visible from the International Space Station (ISS) in that area. Observers note the intense white roofs and the expansive layout that dominate the landscape of the Campo de Dalías.
Located in the Campo de Dalías region, where El Ejido is situated, more than 20,000 hectares are devoted to greenhouses. According to the 2020 Agricultural Census, the entire province of Almería covers about 30,000 hectares of agricultural land, representing roughly half of Spain’s total dedicated to farming, which sits around 65,000 hectares per the National Institute of Statistics (INE). Some later figures from the Junta de Andalucía, referencing 2021, suggested the plastic-covered agricultural area in that state reached 32,000 hectares, hinting that the regional estimate might be conservative in nature.
Approved by Pedro Duque
The Almería greenhouse complex stands out as one of the planet’s largest concentrations of controlled agriculture, making it easily recognizable from space. This recognition was echoed by Pedro Duque, a Spaniard who recently toured the area. He has served as the country’s Minister of Science and Innovation and is also an astronaut who has flown into space. When asked on TVE’s Desafía tu mente whether the Great Wall of China could be seen from space, Duque stated that it could not be seen clearly from orbit. He explained that the wall is not particularly high and is made of the same basic materials as the surrounding terrain. He noted that people sometimes claim to have photographed it from above, but those claims lack substantiation. Even the first Chinese astronaut to photograph the wall acknowledged it is not visible to the naked eye from space.
The observation that remains most evident from space around the Iberian Peninsula is the Almería greenhouse field itself. NASA observations corroborate that the scale of this agricultural complex makes it a prominent feature when viewed from orbit. The distinct, bright expanse of the greenhouses is the most noticeable human-made element in the region, a consequence of both its size and its highly reflective surfaces that bounce sunlight intensely.
NASA publications from recent years underscore that these greenhouses occupy such a vast area that they likely influence local climate by reflecting a lot of sunlight. The white roofs live up to their reputation by reflecting a substantial portion of solar radiation, a factor scientists have considered when discussing potential microclimate effects in the area.
The Almería greenhouse complex is not the only example of large-scale human alterations visible from space. Southeast of Salt Lake City, the Bingham Canyon mine stands out as the largest open-pit excavation on Earth. Other well-known structures, like China’s Three Gorges Dam or Dubai’s Palm Jumeirah, have also been cited by astronauts as visible from orbit. By contrast, there is ongoing debate about whether the pyramids of Egypt can be seen from space with unaided vision, highlighting how visibility from space can be highly subjective and dependent on lighting, altitude, and atmospheric conditions.
In the broader conversation about the Almería greenhouses, researchers observe a notable effect on land reflectivity. Using data from NASA’s MODIS sensors aboard the Aqua and Terra satellites, studies by scientists at the University of Almería show that the surface albedo in this region increased by nearly 10 percent between 1983 and 2006 because of the glassy roofs. This optical change is believed to contribute a cooling effect, estimated at around 0.3°C per decade in Almería, compared with a regional warming of roughly 0.5°C per decade elsewhere in the area.
Estimates suggest the Almería greenhouses now produce between 2.5 and 3.5 million tons of fruits and vegetables annually. The ability to grow tomatoes, peppers, cucumbers, and melons out of season supports European markets, providing significant regional food security and economic activity for residents throughout the continent.
The spread of these facilities also spurs important discussions around environmental impacts, including the fate of plastic waste from the structures and the broader ecological footprint that plastic packaging and mulch can create when it enters land and sea ecosystems. The debate continues as communities weigh economic benefits against long-term environmental costs and the responsibilities tied to plastic waste management.
The sea of greenhouses near El Ejido remains a distinct visual landmark. It is not the only human-made feature that has drawn attention, yet it stands out as a striking example of how large-scale agricultural infrastructure can dominate a landscape to the point of being visible from space, especially when viewed with satellite data and high reflectivity in mind. The conversation about visibility from space blends science, technology, and geography, reminding audiences that what is seen from orbit depends on many variables, including scale, context, lighting, and observer perspective.
In summary, while the Great Wall of China cannot be discerned from space with the naked eye, the Almería greenhouse complex in Spain provides a clear case of a man-made feature that is highly visible due to its size and brightness. The phenomenon offers a real-world example of the interaction between human activity and the planet’s appearance from above, a topic of continuing interest for scientists, policymakers, and space enthusiasts alike.