Tuesday, December 1, 2009

Is the Wall's View From Space that Great?

What is so great about the Great Wall of China? Could it really be the only visible man-made structure from outer space? How is it visible, if it is visible; by camera, or telescope, or the naked eye? From what distance would it be visible from? Is the Great Wall really that great, even from outer space?
In order to bust this myth, a wide range of resources are needed, such as time, money, technology, and astronauts. There could be a wide range of technology used, such as lenses, digital cameras, and an imaging radar. Many obstacles also contribute to the ability to see the Wall, such as the age of the structure, the material it is built out of, and the condition of the atmosphere. Where you are in space also contributes to its visibility. There are so many man-made objects on Earth, so why would people think it was the only visible thing? A possibility could be that the Great Wall is so large, people just figured it was the only visible man-made thing. Is it?







The orange line shows the Great Wall through radar imagery.

The Wall is not the only visible man-made structure from space, although it is visible from space, to an extent. It cannot be seen from the moon, which was a theory that has dated back to 1938, and was disproved when astronauts landed on it. No man-made object is visible from the moon, but plenty are visible from different points in space. The most visible objects from low Earth orbit are cities at night. The Wall can be seen using the Spaceborne Imaging Radar, and a 180mm lens and a digital camera. No one knows for sure if the Wall can be seen with just the naked eye, because a lot of factors play into the visibility, such as the material. The Great Wall of China is built out of earthly materials, making it blend in with the Earth, and hard to spot. So using the right technology, the Wall can be seen from space, but it is not the only thing man-made structure.

These are the pyramids at Giza, and they are man-made structures that are visible from space.

All information and pictures in this post were found at NASA

6 comments:

Katherine & Gabi said...

Ever since I was young,i always have heard that the Great Wall is the only thing that can be seen from outer space. But i guess its not the only thing.So i was wondering what other man made objects can bee seen from outer space. You also mentioned that the Great Wall is hard to see because it is made out of natural materials. So if something is made out of a man made material, would it be easier to see from outer space???

Hannah said...

It makes sense that its not the only thing. I mean wouldn't you be able to see structures such as the Eifell Tower and the Empire State Building? And kitkatbar...i agree would man made material be easier to see from outerspace?

Bethany13 said...

I always believed this myth too because I had heard it was true dozens of times and the great wall is so huge it seems possible. I am also wondering the same thing as kitkatbar, it seems like it wouldn't really matter what the materials were, just the size so how would the materials affect it?

Cammi said...

I am thinking along the same lines as hannah and kitkatbar about the man-made materials. I think that they should try to cover it in glow in the dark stuff and then see if you can really see it from space.

livya said...

If an object is made out of man-made materials that match the colors of the earth, such as the pyramids or the Great Wall, it is harder to see from space.

Ellen R. Herd said...

I have to say I was a little skeptical about this one. Of all the structures on Earth, why would the Great Wall be the only one you could see from space? In light of what you mentioned about it being made of earth materials, I would think it would actually be very difficult to see from space. It makes sense that cities at night would be seen from space, because they are bright and don't blend in with the rest of Earth.