Man-made structures visible from space
Encyclopedia
Man-made structures visible from earth orbit without magnification (by mechanical aids such as a camera or binoculars) include highways, dams, and cities. The most commonly cited example, the Great Wall of China
, is barely visible from low earth orbit
(under perfect conditions), but not from the moon.
Part of the problem of discerning fact from urban legend
is defining how far up "space" is, which could be anywhere from the edge of space at an altitude of 100 kilometres (62.1 mi); to Apollo 12
's orbital at 290 km (180.2 mi); to the moon, which orbits about 381415 km (237,000.9 mi) away. A best estimated definition would be in the hundreds of kilometres into space. Another definition is the Kármán line
, which is at the altitude
of 100 km (62.1 mi) above the Earth
's sea level
. That line is accepted by the Fédération Aéronautique Internationale
(FAI), which is an international standard setting and record-keeping body for aeronautics
and astronautics
, as the boundary between the Earth's atmosphere
and outer space
.
Cities are easily distinguishable from surrounding countryside by both shuttle astronauts in an Earth orbit 135 miles (217.3 km) high as from space station
s, which orbit much higher, circling the planet at c. 250 miles (402.3 km). Using binoculars, the astronauts can see roads, airports, dams, harbors, even large vehicles such as ships and planes. At an orbit of 160 to 350 miles, many such objects are visible from the Space Station.
).
The Great Wall of China
is, proverbially, the man-made object most often cited as being visible from outer space. Claims are made for the factoid that it is visible from the Moon. William Stukeley
mentioned this claim in his letter dated 1754. The claim was mentioned by Henry Norman
in 1895 as if it was already well-known. The issue of "canals" on Mars was prominent in the late 19th century and may have led to the belief that long, thin objects were visible from space.
The claim the Wall is visible has been debunked many times, but is still ingrained in popular culture. The viewer would need visual acuity
17,000 times better than normal (20/20) to see the Wall from the Moon, and vision 8 times better than normal to see it from low earth orbit
.
The "People's House
" in Bucharest, Romania is the second largest building in the world, after The Pentagon
, and has been cited as being visible from space.
is almost invariably described in terms of visibility from space. The BP
Spill or Deepwater Horizon oil spill
of April 20, 2010 was so described in news stories, on scientific websites, as well as jokes about the spill. Algae blooms and sewage
, which are indirectly created by man-made pollution, are visible, and have been photographed, from space.
("the Great Wall of China is the only man-made object visible from the moon"), meme
("Many are familiar with the claim") trivia
questions, metaphor
, urban legend
, and proverb
, that certain constructed objects or effects are so large as to be visible from outer space. For example, a giant beaver dam
in Canada
was described as "so large it is visible from outer space." Field and Stream asked and answered, "How big? Big enough to be visible ... from outer space."
Great Wall of China
The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups...
, is barely visible from low earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
(under perfect conditions), but not from the moon.
Part of the problem of discerning fact from urban legend
Urban legend
An urban legend, urban myth, urban tale, or contemporary legend, is a form of modern folklore consisting of stories that may or may not have been believed by their tellers to be true...
is defining how far up "space" is, which could be anywhere from the edge of space at an altitude of 100 kilometres (62.1 mi); to Apollo 12
Apollo 12
Apollo 12 was the sixth manned flight in the American Apollo program and the second to land on the Moon . It was launched on November 14, 1969 from the Kennedy Space Center, Florida, four months after Apollo 11. Mission commander Charles "Pete" Conrad and Lunar Module Pilot Alan L...
's orbital at 290 km (180.2 mi); to the moon, which orbits about 381415 km (237,000.9 mi) away. A best estimated definition would be in the hundreds of kilometres into space. Another definition is the Kármán line
Karman line
The Kármán line lies at an altitude of above the Earth's sea level, and is commonly used to define the boundary between the Earth's atmosphere and outer space...
, which is at the altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
of 100 km (62.1 mi) above the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
. That line is accepted by the Fédération Aéronautique Internationale
Fédération Aéronautique Internationale
The Fédération Aéronautique Internationale is the world governing body for air sports and aeronautics and astronautics world records. Its head office is in Lausanne, Switzerland. This includes man-carrying aerospace vehicles from balloons to spacecraft, and unmanned aerial vehicles...
(FAI), which is an international standard setting and record-keeping body for aeronautics
Aeronautics
Aeronautics is the science involved with the study, design, and manufacturing of airflight-capable machines, or the techniques of operating aircraft and rocketry within the atmosphere...
and astronautics
Astronautics
Astronautics, and related astronautical engineering, is the theory and practice of navigation beyond the Earth's atmosphere. In other words, it is the science and technology of space flight....
, as the boundary between the Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
and outer space
Outer space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
.
Cities are easily distinguishable from surrounding countryside by both shuttle astronauts in an Earth orbit 135 miles (217.3 km) high as from space station
Space station
A space station is a spacecraft capable of supporting a crew which is designed to remain in space for an extended period of time, and to which other spacecraft can dock. A space station is distinguished from other spacecraft used for human spaceflight by its lack of major propulsion or landing...
s, which orbit much higher, circling the planet at c. 250 miles (402.3 km). Using binoculars, the astronauts can see roads, airports, dams, harbors, even large vehicles such as ships and planes. At an orbit of 160 to 350 miles, many such objects are visible from the Space Station.
Cities at night
Metropolitan areas are readily visible at night, particularly in industrialized countries, due to a multitude of street lights and other light sources in urban areas (see light pollutionLight pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...
).
The Great Wall of China
- Main article: Great Wall of China
The Great Wall of China
Great Wall of China
The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups...
is, proverbially, the man-made object most often cited as being visible from outer space. Claims are made for the factoid that it is visible from the Moon. William Stukeley
William Stukeley
William Stukeley FRS, FRCP, FSA was an English antiquarian who pioneered the archaeological investigation of the prehistoric monuments of Stonehenge and Avebury, work for which he has been remembered as "probably... the most important of the early forerunners of the discipline of archaeology"...
mentioned this claim in his letter dated 1754. The claim was mentioned by Henry Norman
Henry Norman
Sir Henry Norman, 1st Baronet PC was an English journalist and Liberal politician. Norman was educated privately in France and at Harvard University, where he obtained his B.A...
in 1895 as if it was already well-known. The issue of "canals" on Mars was prominent in the late 19th century and may have led to the belief that long, thin objects were visible from space.
The claim the Wall is visible has been debunked many times, but is still ingrained in popular culture. The viewer would need visual acuity
Visual acuity
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
17,000 times better than normal (20/20) to see the Wall from the Moon, and vision 8 times better than normal to see it from low earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
.
Other buildings and constructed objects
"The naked eye can tell the difference between cities and countryside from space."The "People's House
Palace of the Parliament
The Palace of the Parliament in Bucharest, Romania is a multi-purpose building containing both chambers of the Romanian Parliament. According to the Guinness Book of World Records, the Palace is the world's largest civilian administrative building, most expensive administrative building, and...
" in Bucharest, Romania is the second largest building in the world, after The Pentagon
The Pentagon
The Pentagon is the headquarters of the United States Department of Defense, located in Arlington County, Virginia. As a symbol of the U.S. military, "the Pentagon" is often used metonymically to refer to the Department of Defense rather than the building itself.Designed by the American architect...
, and has been cited as being visible from space.
Pollution
Large-scale pollutionPollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
is almost invariably described in terms of visibility from space. The BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
Spill or Deepwater Horizon oil spill
Deepwater Horizon oil spill
The Deepwater Horizon oil spill is an oil spill in the Gulf of Mexico which flowed unabated for three months in 2010, and continues to leak fresh oil. It is the largest accidental marine oil spill in the history of the petroleum industry...
of April 20, 2010 was so described in news stories, on scientific websites, as well as jokes about the spill. Algae blooms and sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
, which are indirectly created by man-made pollution, are visible, and have been photographed, from space.
Popular culture
The concept has entered popular culture as a factoidFactoid
A factoid is a questionable or spurious—unverified, incorrect, or fabricated—statement presented as a fact, but with no veracity. The word can also be used to describe a particularly insignificant or novel fact, in the absence of much relevant context...
("the Great Wall of China is the only man-made object visible from the moon"), meme
Meme
A meme is "an idea, behaviour or style that spreads from person to person within a culture."A meme acts as a unit for carrying cultural ideas, symbols or practices, which can be transmitted from one mind to another through writing, speech, gestures, rituals or other imitable phenomena...
("Many are familiar with the claim") trivia
Trivia
The trivia are the three lower Artes Liberales, i.e. grammar, rhetoric and logic. These were the topics of basic education, foundational to the quadrivia of higher education, and hence the material of basic education, of interest only to undergraduates...
questions, metaphor
Metaphor
A metaphor is a literary figure of speech that uses an image, story or tangible thing to represent a less tangible thing or some intangible quality or idea; e.g., "Her eyes were glistening jewels." Metaphor may also be used for any rhetorical figures of speech that achieve their effects via...
, urban legend
Urban legend
An urban legend, urban myth, urban tale, or contemporary legend, is a form of modern folklore consisting of stories that may or may not have been believed by their tellers to be true...
, and proverb
Proverb
A proverb is a simple and concrete saying popularly known and repeated, which expresses a truth, based on common sense or the practical experience of humanity. They are often metaphorical. A proverb that describes a basic rule of conduct may also be known as a maxim...
, that certain constructed objects or effects are so large as to be visible from outer space. For example, a giant beaver dam
Beaver dam
Beaver dams are dams built by beavers as protection against predators such as coyotes, wolves, and bears, and to provide easy access to food during winter. Beavers work at night and are prolific builders, carrying mud and stones with their fore-paws and timber between their teeth...
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
was described as "so large it is visible from outer space." Field and Stream asked and answered, "How big? Big enough to be visible ... from outer space."