PDA

View Full Version : Seeing the Great Wall of China from space (Myth?)



countrywideoptionone
2004-Mar-12, 11:17 PM
I saw this article today http://news.yahoo.com/news?tmpl=story&u=/ap/20040312/ap_on_re_as/china_great_wall_myth_1 Is this accurate, and if so does anyone know the history beind it (besides what it says in the link) and perhaps why it wasn't debunked sooner? I googled the BA site, but I didn't see anything that popped up right away.

edit: forgot to put "from space" in subject

ToSeek
2004-Mar-13, 12:04 AM
The truth is that the Great Wall is visible from space if you really know where to look:

What's Really Visible from Space (http://www.space.com/scienceastronomy/visible_from_space_031006.html)

China's Astronaut Didn't See Great Wall (http://www.space.com/scienceastronomy/great_wall_031017.html)

However, it's not visible from the Moon, and neither is just about anything else artificial.

Grand_Lunar
2004-Mar-13, 03:23 AM
Surprised the BadAstro hasn't tackled this one (or has he?).
Anyway, the Great Wall of China is visible from orbit, but not the moon, like peopl will claim. Astronauts had a hard time just seeing continents. [/i]

sarongsong
2004-Mar-13, 05:51 AM
Friday, March 12, 2004
"China ends Great Wall space myth"
http://makeashorterlink.com/?V25F334B7

Eroica
2004-Mar-13, 09:35 AM
The Great Wall of China is visible from Earth orbit
The problem with a quote like this is that it's too vague. The Moon, for example, is in Earth orbit, but you can't see the Great Wall with the unaided eye from the Moon.

Grand_Lunar
2004-Mar-13, 08:20 PM
The Great Wall of China is visible from Earth orbit
The problem with a quote like this is that it's too vague. The Moon, for example, is in Earth orbit, but you can't see the Great Wall with the unaided eye from the Moon.

Quite right. For accuraccy, low Earth orbit is better. Would that altitute be the "standard" orbit we always here about in Star Trek?

Brady Yoon
2004-Mar-14, 08:59 PM
I think this is definitely a myth. I would think the only things you can seee from the moon are the oceans, continents, and clouds

Archer17
2004-Mar-14, 09:46 PM
Seems not everyone agrees with the Chinese assessment. From space.com:
Apollo 17 astronaut Gene Cernan -- who walked on the moon in December 1972 -- told the Straits Times newspaper he viewed China's most famous monument from space. He said it's a matter of having good eyes and knowing where to look. Regarding the orbital parameters, Gene Cernan goes on to add:
"At Earth orbit of 160 kilometers (100 miles) to 320 kilometers (200 miles) high, the Great Wall is indeed visible to the naked eye." The article can be found here (http://space.com/scienceastronomy/great_wall_040314.html).

Andromeda321
2004-Mar-15, 05:06 AM
One of my violin buddies is the daughter of a former astronaut. He was giving a talk at my school a few months back and I asked him about the Great Wall of China thing. He said he saw it on his second mission but it was a heck of a lot easier to find the pyramids. Also, some of the structures in cities are easier to pick out at nighttime (such as an airport with its lighted runways) because in cities most everything is just plain gray.

Eroica
2004-Mar-15, 12:23 PM
You can probably also see the Suez Canal from low Earth-orbit.

HAVOC451
2004-Mar-15, 12:41 PM
However, it's not visible from the Moon, and neither is just about anything else artificial.

Does this include Europe and North America at night?

ToSeek
2004-Mar-15, 02:21 PM
However, it's not visible from the Moon, and neither is just about anything else artificial.

Does this include Europe and North America at night?

That's an interesting question. Lights at night are the most apparent evidence of artificiality, but I'm not sure if they're visible from the Moon.

kucharek
2004-Mar-15, 02:26 PM
When you are on the moon and most of the earth is dark, the earth is close to the sun. I guess, it's mostly an eye adaption problem.

Harald

Manchurian Taikonaut
2004-Mar-15, 02:40 PM
some news on the subject
#
http://www.spacedaily.com/2004/040315040505.ou3ws93d.html

people have photographed many objjects fron space, such as the pyramids and other objects from the ISS

AndrewGPaul
2004-Mar-15, 10:57 PM
The Great Wall thing always seemed odd to me. I mean, it's long, but thin. And it looks to me like the contrast between it and the surroundings is lower than, say, a river and the ground. However, if someone who's actually been up there says he could see it, I'll take his word for it, until I get a chance to check for myself.

Eroica
2004-Mar-16, 08:08 AM
It always struck me as odd too. I mean, the Great Wall is only as wide and as tall as a small house. Only its length is unusual. Does this mean that you can see a small house from LEO [low Earth-orbit], only you don't realize it because it's just a featureless dot?

eburacum45
2004-Mar-16, 08:23 AM
The Great Wall itself would almost certainly be invisible but it acts as aterminator or boundary between different parts of the countryside- the land use might very different on each side of the wall, and this would make the Wall itself very visible.

However this would not be visible from the Moon; even massive land reclaimation projects like those in Holland, which must be the largest man made features of the Earth, woul be too small to see.

Paul Beardsley
2004-Mar-16, 04:32 PM
There was a lovely variant on this in the comedy series Father Ted. The priest had offended some Chinese, so he did a sycophantic talk and slide show to try and make amends. He showed a slide of the Wall and said, "This is the Great Wall of China. It is so big it can be seen from anywhere in the world!"

countrywideoptionone
2004-Mar-17, 11:54 PM
Looks like several different ideas are here, which follows from what the different people who have been in orbit have said. The man from China said he could not see it, and that's the reason it's being pulled from the textbooks in China. Perhaps it's a case of believing you're seeing something because you want to see it. Perhaps not. As far as pictures go, I'd say that through a camera lens you can pick out many features that could not be distinguished with the eye alone. So a picture of the wall from orbit does not prove that the eye alone can find it from orbit.

Jpax2003
2004-Mar-18, 08:09 AM
snopes.com says no (http://www.snopes.com/science/greatwal.htm)

countrywideoptionone
2004-Mar-19, 12:28 AM
snopes.com says no (http://www.snopes.com/science/greatwal.htm)

Thanks for the link

kucharek
2004-Mar-22, 10:49 AM
The Great Wall of China is visible from Earth orbit
The problem with a quote like this is that it's too vague. The Moon, for example, is in Earth orbit, but you can't see the Great Wall with the unaided eye from the Moon.

Quite right. For accuraccy, low Earth orbit is better. Would that altitute be the "standard" orbit we always here about in Star Trek?

I just saw the ST:VOY epsisode 11:59 (http://www.startrek.com/startrek/view/series/VOY/episode/105968.html).
In the opening, Neelix tells Janeway that until the 21st century, the Chinese Wall was the only building that could be seen from orbit. So, the Star Trek standard orbit seems to be a lot higher than LEO. ;-)

Harald

George
2004-Mar-28, 10:34 PM
Looks like they are giving the final word to their first astronaut(?).

CNN article...

For decades, the Chinese propagated the myth that their most famous creation was visible from space. Elementary-school textbooks in the world's most populous nation still proclaim that the structure can be seen by the naked eye of an orbiting cosmonaut.

But the myth was shattered upon Yang Liwei's return from a 21 1/2-hour space jaunt last year, so schoolbooks will be rewritten, the Beijing Times newspaper reported Friday.

Full Story here... here (http://www.cnn.com/2004/WORLD/asiapcf/03/12/china.great.wall.myth.ap/index.html)

I don't know what to believe, frankly. Maybe if the sun's reflection is just right off the wall, it will make it visible. Also, I wonder what sort of orbit Yang had to view the wall.

If it is visible...
What is it called when you debunk a debunk? #-o A reverse debunk, touche bunk, bunk-a-boo, debunkity debunk, un-debunk, anti-debunk? :roll:

[The article also says NASA claims you can't see the wall.]

Sam5
2004-Mar-28, 11:12 PM
I don't know what to believe, frankly.

There might be long stretches of the Great Wall that has rocks and debris cleared away for hundreds of yards on each side of it, rocks that were used in its construction, also trees and shrubs cleared away. Astronauts in low orbit could possibly see wide straight lines (the cleared areas), hundreds of yards wide, but not the wall itself.

JohnOwens
2004-Mar-29, 11:19 AM
If it is visible...
What is it called when you debunk a debunk? #-o A reverse debunk, touche bunk, bunk-a-boo, debunkity debunk, un-debunk, anti-debunk? :roll:
De-ja-bunk?

George
2004-Mar-29, 04:34 PM
I suspect a low altitude orbit and, possibly, a little help from the right angle of sunlight on the wall might allow a carrot-eating astronaut see it from space.

March 24 article in Space Daily.... here (http://www.spacedaily.com/news/china-04q.html)

Adding another twist, veteran American astronaut Gene Cernan has insisted the Great Wall of China can be seen with the naked eye from outer space. Cernan, the last man to walk on the moon as commander of the Apollo 17 mission, said he has seen the Great Wall from Earth's orbit, although he could not do so while on the moon.

"In Earth's orbit at a height of 160 to 320 kilometers, the Great Wall of China is indeed visible to the naked eye," he was quoted as saying during the recent Asian Aerospace exhibit in Singapore.

ToSeek
2004-May-12, 03:34 PM
Great Wall from space (http://www.space.com/imageoftheday/image_of_day_040512.html)

ToSeek
2004-May-20, 05:49 PM
Great Wall from space (http://www.space.com/imageoftheday/image_of_day_040512.html)


Or not. (http://www.esa.int/esaCP/SEMNA5HHZTD_index_0.html)

samseed
2004-May-21, 11:53 PM
This question was answered in a live interview with the astronauts on the ISS approximately 2 months ago. (one using a translator of course). But if I recall correctly, they said that it was very hard to see the wall because it blends in with the surrounding area. There isn't a lot of color contrast to pick it out. They did say that they could see cities and the pyramids of Egypt though.

Anyone else hear that live interview?

Launch window
2005-Mar-20, 11:18 AM
The Great Wall of China is visible from Earth orbit
The problem with a quote like this is that it's too vague. The Moon, for example, is in Earth orbit, but you can't see the Great Wall with the unaided eye from the Moon.

Quite right. For accuraccy, low Earth orbit is better. Would that altitute be the "standard" orbit we always here about in Star Trek?

I just saw the ST:VOY epsisode 11:59 (http://www.startrek.com/startrek/view/series/VOY/episode/105968.html).
In the opening, Neelix tells Janeway that until the 21st century, the Chinese Wall was the only building that could be seen from orbit. So, the Star Trek standard orbit seems to be a lot higher than LEO. ;-)

Harald


US astronaut Eugene Cernan says its visible


ESA's Proba satellite here shows a winding segment of the 7240-km long Great Wall of China situated just northeast of Beijing. The Great Wall's relative visibility or otherwise from orbit has inspired much recent debate.

http://esamultimedia.esa.int/images/Proba/cina.jpg

...'but I did not see our Great Wall," Liwei said after returning from his Space flight

People called for Chinese school textbooks to be revised to take account of Liwei's finding.


However such revisions may be unnecessary, according to American astronaut Eugene Cernan, speaking during a visit to Singapore: "In Earth's orbit at a height of 160 to 320 kilometres, the Great Wall of China is indeed visible to the naked eye.

http://www.esa.int/SPECIALS/Proba_web_site/SEMTTHGHZTD_0.html
Washington DC from Space
http://www.nasa.gov/centers/goddard/images/content/95113main_wash_tm.jpg
I like some of the other features picked up by NASA or ESA satellites such as the Egyptian Pyramids or the Nile delta
http://rst.gsfc.nasa.gov/Intro/pyramids512.jpg

So when people look at the 'Great Wall' are they actually looking at rivers, or does anybody here know what size, lenght, width the area around the wall is.....
and what resolving power the human eye has at these Earth orbiting heights & viewing through atmosphere would make it more difficult ?
Satellites and instruments on space telescope have very good designs, giving them far superior spatial resolution to the human eye

John Kierein
2005-Mar-20, 04:27 PM
I worked on the Skylab experiments. One of the interesting things visible from Skylab was the border between New Mexico and Texas! Laws were visible from space! It turns out that Texas law allowed more irrigation than New Mexico and the difference was clearly visible.

Bad Dr Galaxy
2005-Mar-22, 12:00 AM
Check this out:


http://www.snopes.com/science/greatwal.htm

lti
2005-Mar-22, 12:12 AM
if a large motorway (or highway or whatever u guys call them) is not visible from space, why should the great wall of China?

Surely there are motorways in america that would be wider, straighter and longer than the great wall? If so, are they visible?

It seems highly unlikely that anyone could see the great wall from an orbit of 300km or however high space shuttles tend to orbit.

edit: read the snopes links. it covers all this.

Joe87
2005-Mar-22, 01:32 AM
I worked on the Skylab experiments. One of the interesting things visible from Skylab was the border between New Mexico and Texas! Laws were visible from space! It turns out that Texas law allowed more irrigation than New Mexico and the difference was clearly visible.

This is also true in California. The Imperial Valley in CA is heavily irrigated, whereas just across the border in Mexico, it is not. The border is quite obvious in satellite photos. Not sure if this is due to Mexican law discouraging irrigation, treaties with Mexico regarding Colorado River water, or maybe it's just that all the irrigation water is used up by the US before the Colorado River gets to Mexico.
http://edcwww.cr.usgs.gov/earthshots/slow/Imperial/Mexicali1973

Bad Dr Galaxy
2005-Mar-22, 03:51 PM
In the snopes webpage I linked to above, they summarize the
origin of the Great Wall from the Moon legend as best they can:


Where did this belief come from? The exact source is unknown, but the earliest citing we have comes from Richard Halliburton's Second Book of Marvels, the Orient, published in 1938, which states that "Astronomers say that the Great Wall is the only man-made thing on our planet visible to the human eye from the moon." Halliburton was an adventurer-lecturer whose travel writings were extremely popular and sold quite well during the first half of the twentieth century (and who wasn't above spinning tall tales in order to enthrall an audience), and if he himself wasn't the originator of this factoid, he undoubtedly helped it to spread widely.

So it looks like a case of someone fancifully saying something to enhance
the mystique of something (in this case, the Great Wall) and people
uncritically accepting it for decades, until it becomes one of those
things "everybody knows."

Evan
2005-Mar-22, 07:26 PM
At low sun angles the wall should cast a pretty long shadow like a scarp on the moon. That should be visible from LEO.

How about knubed?

mopc
2005-Mar-23, 05:10 AM
Yeah, its like that 10% of our brain thing... I believe the man made things most clearly visible from space would be the cities, vastly bigger than any individual object.

I mean, the great Wall cannot be more visible than an average road.

And from the MOON??? No way - the earth seen from the moon is as wide as a human thumb seen with the arms stretched out - you're lucky if you see the continents!

Evan
2005-Mar-23, 07:04 AM
Roads don't usually cast much of a shadow.

Launch window
2005-May-02, 03:06 PM
The Wall of China has be seen from Space again
link
(http://www.newscientist.com/channel/space/mg18624964.100)

it's not the only thing that can be spotted, man-made briges, and illuminated areas of a city, and Pyramids have been seen aswell, newscientist did the news item

Maksutov
2005-May-02, 04:13 PM
Anything is visible from anywhere if you have the right resolution and light gathering power.

This whole thing reminds me of the ads that used to (I hope the past tense is true!) run in such magazines as Popular Science.

"See 50 miles!" they would boldly proclaim about the incredible powers of the cheap binoculars they were advertising.

I would read that, and, then, if the time of year and conditions were right, go outside and look with my unaided eyes at M31, thereby being able to "See 17,036,344,852,881,172,480 miles!" without their low-quality binoculars.

Same deal applies to space. The Great Wall will show up if you're at the right altitude, the lighting is right re shadows, and you've got the right resolution (i.e., in LEO, if your eyes aren't too bad). It's good to remember here that Gemini astronauts talked about being able to see the wakes of boats in harbors. Any sailors out there will know what the approximate horizontal size and vertical relief of those wakes were.

Yet another example of the media trying to set some kind of absolute standard to something that is variable. Very silly.

V-GER
2005-May-13, 01:11 AM
Here's latest from Nasa:

http://www.nasa.gov/vision/space/workinginspace/great_wall.html

Maksutov
2005-May-13, 01:45 AM
Here's latest from Nasa:

http://www.nasa.gov/vision/space/workinginspace/great_wall.html
Thanks for the update. NASA seems to have forgotten what one of their own astronauts saw (Cernan).

BTW, it's all that yellow light from the Sun that makes it stand out. :D

Maksutov
2005-May-13, 01:55 AM
BTW, there's an area in that photo that contains this pattern.

http://img178.echo.cx/img178/6714/chinagridfromspace7iq.th.jpg (http://img178.echo.cx/my.php?image=chinagridfromspace7iq.jpg)

It's toward the upper right-hand corner. The grid of a started but never completed city? :-k

01101001
2005-May-13, 02:20 AM
Here's latest from Nasa:

http://www.nasa.gov/vision/space/workinginspace/great_wall.html
Well, they certainly drove this point home:


Kamlesh P. Lulla, NASA's chief scientist for Earth observation at Johnson Space Center in Houston, directs observation science activities from the Space Shuttle and the International Space Station. He says that generally the Great Wall is hard to see and hard to photograph, because the material from which it is made is about the same color and texture as the area surrounding it.
Anything worth saying is worth saying twice:


Of the wall visibility theories, Lulla said: "A lot has been said and written about how visible the wall is. In fact, it is very, very difficult to distinguish the Great Wall of China in astronaut photography, because the materials that were used in the wall are similar in color and texture to the materials of the land surrounding the wall -- the dirt."

V-GER
2005-May-13, 06:44 PM
Maksutov wrote:

The grid of a started but never completed city?

Looks strange alright... what else could it be?

Maksutov
2005-May-14, 09:18 AM
Maksutov wrote:

The grid of a started but never completed city?

Looks strange alright... what else could it be?
Well, hang on, but back in the 1950s I read a "pulp" style sci-fi magazine that claimed that the Chinese were all aliens, having arrived on Earth about 5000 years ago. Variants on this persist to this day. (http://www.burlingtonnews.net/dropas.html) Perhaps this grid is some kind of signaling device to their ancestors that Earth is now ready for more "emigration" (or deportation). :wink:

I'm amazed I remembered that, since the same issue had all sorts of stills from This Island Earth presented as "[almost] fact". The series with Faith Domergue being stripped down by the "conversion tube" was an eye-grabber! :D

frogesque
2005-May-14, 12:09 PM
Maksutov wrote:

The grid of a started but never completed city?

Looks strange alright... what else could it be?
Well, hang on, but back in the 1950s I read a "pulp" style sci-fi magazine that claimed that the Chinese were all aliens, having arrived on Earth about 5000 years ago. Variants on this persist to this day. (http://www.burlingtonnews.net/dropas.html) Perhaps this grid is some kind of signaling device to their ancestors that Earth is now ready for more "emigration" (or deportation). :wink:

I'm amazed I remembered that, since the same issue had all sorts of stills from This Island Earth presented as "[almost] fact". The series with Faith Domergue being stripped down by the "conversion tube" was an eye-grabber! :D

Hey! there's a seperate thread for You know you're getting old when....
(http://www.badastronomy.com/phpBB/viewtopic.php?t=20599&start=175&sid=5d741dae354d8e 1648bafbb88d2ef027) :lol:

That said - a stripped down version of Faith Domergue (http://www.freelance-help.com/art/10042211.html) would definitely be memorable 8)

Minbari
2005-May-14, 12:15 PM
What I heard is the wall is easly visible from space with IR vision at night, though as many of the comments here say it can be faintly seen if one knows exactly when and where to look, but the entire lenght is hard to distinguish.

At least thats what I know.

frogesque
2005-May-14, 04:36 PM
BTW, there's an area in that photo that contains this pattern.

http://img178.echo.cx/img178/6714/chinagridfromspace7iq.th.jpg (http://img178.echo.cx/my.php?image=chinagridfromspace7iq.jpg)

It's toward the upper right-hand corner. The grid of a started but never completed city? :-k

Looks kind of big for a city plan - perhaps an ancient field irrigation system ???

Yalius
2005-May-20, 05:39 AM
I had read that the mountainous ridge the Great Wall sits upon is what's lightly visible, not the wall itself.

Kiwi
2005-May-20, 10:01 AM
I can't beat the 1938 story, but distinctly remember reading a comic in the late 50s or early 60s that included the story about the Great Wall being visible from space. In fact, it's the only story I particularly remember from a comic at that time.

The comic was probably one of those black-and-white 100-pagers we used to buy that was full of all sorts of heroes. Anyway, some aliens set up a second Earth and the hero, who was out in space, had to choose the correct one or something diabolical would befall mankind. He did it by finding the Great Wall -- the aliens had not created it on their fake planet.

gopher65
2005-May-20, 07:39 PM
IIRC the resolution of the best spy sats in low orbit is ~2 meters per pixel, mainly due to atmospheric distortion.