Monstrous Mike
09-27-2004, 06:01 AM
I guess ever since I was a kid, I held the following to be true: "The Great Wall of China is the only man-made object visible from space".
It's really just a benign statement, something to throw around at the campfire. It seems to be common knowledge among most people, something we grew up with and never questioned. It is so common in fact that it even appears in children's textbooks. However, upon some investigation, it appears this statement is simply untrue.
Two sources of information to verify this claim are testimony from astronauts who have looked out of the window of a spacecraft in orbit and satellites which take pictures at 1x magnification. According to both sources, the Wall is actually very difficult to see since it is similar in color to the surroundings and not really that wide. Actually, the first Chinese man in space reported that he could not see it. And there are many other man-made objects that can be seen like airports, highways, etc.
Another myth that I held true for years was that water in a toilet or drain would rotate depending on which hemisphere you are in. The source for verifying this is more scientific that the man-made object from space myth. The Coreolis Effect is very real and well understood. If you have recently looked at a weather map showing hurricanes you can see that they are rotating and that they rotate in different directions depending on which side of the equator you are on. However, this force is so small on a bowl full of water that drains in less that a minute that it has no effect. The initial motion of the water has a thousand-fold more effect than the rotation of the earth. To get a toilet bowl to rotate down a drain according to the hemisphere you are in would require a special room which is completely vibration-free, the water to rest for several days and then drain over a 24 hour period. Then, you could constantly predict the direction of rotation.
So what is the point of this post? Well my point is that I don't care who you are or how much you think you know, you probably believe in some things that are not true. The above are two (simple) examples in my life where I had to change my thinking.
It's simply something to ponder the next time you say you are sure about something.
It's really just a benign statement, something to throw around at the campfire. It seems to be common knowledge among most people, something we grew up with and never questioned. It is so common in fact that it even appears in children's textbooks. However, upon some investigation, it appears this statement is simply untrue.
Two sources of information to verify this claim are testimony from astronauts who have looked out of the window of a spacecraft in orbit and satellites which take pictures at 1x magnification. According to both sources, the Wall is actually very difficult to see since it is similar in color to the surroundings and not really that wide. Actually, the first Chinese man in space reported that he could not see it. And there are many other man-made objects that can be seen like airports, highways, etc.
Another myth that I held true for years was that water in a toilet or drain would rotate depending on which hemisphere you are in. The source for verifying this is more scientific that the man-made object from space myth. The Coreolis Effect is very real and well understood. If you have recently looked at a weather map showing hurricanes you can see that they are rotating and that they rotate in different directions depending on which side of the equator you are on. However, this force is so small on a bowl full of water that drains in less that a minute that it has no effect. The initial motion of the water has a thousand-fold more effect than the rotation of the earth. To get a toilet bowl to rotate down a drain according to the hemisphere you are in would require a special room which is completely vibration-free, the water to rest for several days and then drain over a 24 hour period. Then, you could constantly predict the direction of rotation.
So what is the point of this post? Well my point is that I don't care who you are or how much you think you know, you probably believe in some things that are not true. The above are two (simple) examples in my life where I had to change my thinking.
It's simply something to ponder the next time you say you are sure about something.