Why can see the  great wall from air space?
965981
This question is asked very often, and sometimes it is not phrased correctly, just like: "Can you see the Great Wall of China from the shuttle or from the space station?". Of course you can see it from there! (Although personally I was not able to see it, as our inclination was not enough, or to put it in other words: our mission did not take us over that Wall.) In the special programme "Looking down on the Earth with Marilyn Monroe" I thoroughly explained that everything larger than 30 metres can be recognised with the naked eye from a near Earth orbit. And of course also the Great Wall. \n\nBut the well-known rumour is as follows: "Is the Great Wall of China the only man-made work (incl. cities etc.) that you can see from the Moon?" As (unfortunately) I cannot answer this question from my own personal experience, I asked two of my Apollo colleagues - Charles M. Duke (Apollo 16, 5th moonlanding, April 1972) and Eugene A. Cernan (Apollo 17, 6th moonlanding, December 1972) - to enlighten us with the answer. Their answer was as follows:\n\nCharles M. Duke (Apollo 16): "... I do not think that you can see anything created by mankind from the Moon. Nobody saw the Great Wall of China from the Moon. You cannot see any large cities or man-made objects from the Moon. It is already difficult enough to see the different continents from the Moon. ... It is a common misunderstanding that we were able to see the Great Wall of China from the Moon. I do not know how this came about."\n\nEugene A. Cernan (Apollo 17): "There are NO man-made objects that you could see from the distance of the Moon, neither with your naked eye nor with the monocular we had with us on the Apollo mission. ... Yes, you can see the Great Wall of China from 200-300 miles, from the Earth orbit of the shuttle, in space. I could also see the Dome Stadium in Houston on Gemini IX with my naked eye. But these things, including large cities, cannot be seen from the Moon neither during the day nor at night. ... You should realise that the Earth, which appears four times larger than the Moon , is covered in oceans and clouds. From the Moon, we see the Earth just as the Lord created it, we do NOT see any man-made objects." \n\n\nI think this is an answer to this probing question once and for all.
797655
http://en.wikipedia.org/wiki/Great_Wall\n\nThe above link will help you will all the questions, you may have on the Great Wall Of China, Good luck
628286
Yes, I did. I was sitting in my garden watching the sky, but not for the ISS. I saw it by coincidence. It looks like a bright star (or a highly illuminated plane), moving very fast. In 30 min - 1h it cross the entire night sky, disappears over the horizon, then reappears in 30 min - 1h almost diametrical. I`m from Romania 44 degrees 59` 38`` lat N and 25 degrees 44` 34`` long E. I have no idea how or if can be seen from others places. If you can, watch it just once how it crosses the sky. It`s beautiful. And knowing that human kind put it there give you a great sentiment.
1042536
I can't even see it on Google Earth without having to zoom in. I can't believe astronauts have such great vision they can zoom in and see something 20-30 feet wide from a quarter million miles away. Anyone that belives that will believe anything.
657574
A well built wall will also become a tourist attraction.  Look at all of the people who travel to China and visit the Great Wall.  (My friend went to China and visited the wall.  She said it is a major attraction.)\n\nWhat an idea.
1127386
I can think of 2 possibilities.  One is when they use an occulting disk to block out the Sun (because it is so bright), so you see a black disk, and then you can see the space around the Sun.  They do that to look at the atmosphere around the Sun.  Take a look at the first link below.\n\nThe other possible answer is that the photographs are not taken in normal visible light but some other wavelength.  in the second link, there is a picture where the Sun's 'normal' surface looks dark.  The caption helps explain it.
635617
The great wall was built by people..the grand cayon is the result of water movement causing erosion.   The great wall is above ground, the grand canyon is below ground level.  The great wall took several generations to build. The grand cayon took several milenia to form.  The great wall is deteriorating, the grand canyon keeps growing little by little.
66085
Earth is around, you know that. An aero plan has to fly around and it would be flying thousands of kilometers away from you.\n\n It would appear that the plane is flying so slowly. But if you see an aero plane that is flying on low altitude that would appear to be faster.\n\nSky is so wide, you can see larger area if you look further and further you can see more wide angle. \n\nIt is not same as if it is closer to you, the distance would be very small. If it is far distance is greater.
394180
It has to do with refraction due to different densities of air-in cooler climates, there tends to be much warmer air near the surface, with colder air in higher altitudes, plus the colder air is much more dense, so acts like a magnifying lense- The very largest moon-views are always seen close to the horizon because of this.
738887
Good question! I want to know about it too\n\n:/ maybe something to do with the wonder wall in china? XDDDD who knows?
902957
Aerial.  Its from space.
512696
My guess is you are talking about being able to see the flashing lights of a plane at night but cant hear it. Or seeing a high plane with contrails during the day but cant hear that either. Light travels 186,282 mps while sound is only 1100 feet per second. So you see something your mind knows is making noise, but cant hear it because of the distance. Now if the sound has not dispersed through the air by the time it gets to you, then you hear it, but since you cant see what is making it, you dont realize it.
123930
Atmospheric distortions causes difficulties in truly viewing far away objects and the farther they are the greater the distortion. That is why observatories are often built high up in mountains to lessen interference from atmosphere as well as light pollution. Ideally satellites are left in orbit in space function best of all without these influences and the best pictures taken of stars and galaxies are achieved by these.
400598
All of the light "floating" in the air is composed of photons which are eventually absorbed by the atoms in the room and converted into heat.  This heat eventually dissapates through the walls and radiates outside the room.  Of course, there is an imperceptable delay between when the last photon leaves the light and is absorbed by the walls, but this happens at the speed of light and can't be seen by you or me.
65641
Check Discovery and A&E group shows.  The Great Wall is actually lots of walls built over a long period of time using varying techniques according to technology, terrain, and available materials.
736872
It's an optical illusion. When it's near the horizon there are points of reference within your field of vision so your brain can correctly assess the size of it whereas high in the sky, there's nothing for the brain to use to assess size.
26407
Well, according to most theories, the Universe does not have a 'wall', if by wall you mean boundry.  However, solar systems do have a 'wall'.  This wall is called the heliopause, and marks the boundry where a star's solar winds fade into the interstellar void (the space between the stars).  Any object passing through the heliopause is believed to experience a termination shock.  This is caused by the preasure difference between the solar winds and the void NOT because the object is actually hitting a wall or other physical barrier.  Today, many theories also (as the previous post mentions) suggest that the Universe is both finite yet boundless.  What does this mean?  First, 'finite' means that the Universe is not infinate in size (theoretically we could then assign a number to the its size, much like we assign a number to the size of a piece of land).  However, the Universe has no boundries - it is 'boundless'.  How can something have a finite size and no boundry?  One theory is that the Universe has a shape like a ball.  Imagine you are a tiny person walking on the surface of a basketball.  Assume you can only walk and not fly, jump, etc. No matter how much you walk in any direction, you'll never find an 'edge' (to you, the basketball has no boundry).  However, if you remove the skin from the basketball and lay it flat, it is apparent that the basketball _does_ have a finite (limited) size.  It's hard to imagine it, but picturing the Universe 'flat' and 'wrapped around' itself in a ball (a closed Universe) will allow you to have a Universe without boundries, but with a definate size.  Our minds are not equiped to visualize objects beyond the 3rd dimention (for example, we can't 'see' space-time), so most modling of the Universe makes the most 'sense' when done in calculations.