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Night Vision And Humans: Why Can't We See Color?
夜視：人類為何看不見顏色？
When we are in a fairly dark room, or outside at night away from lights, we can still see, but we can't see the colors of things very well. Why is that?
當我們在一個非常昏暗的房間或夜晚在無燈的戶外，我們仍然可以看見物體，但很看不清楚物體的顏色，為什么會這樣呢？
There are two kinds of light-sensitive organs located in the backs of our eyes: rod-shaped and cone-shaped. Both rods and cones are sensitive to light. The difference between them is that the rods allow us to see in very dim light but don't permit detection of color, while the cones let us see color but they don't work in dim light.
在我們眼睛的后部有兩種感光器官：桿狀體和錐狀體，它們都對光線敏感。而它們的差別就在于，桿狀體能讓我們看見昏暗的光線下的東西，但無法辨別顏色；而錐狀體能讓我們辨別物體的顏色，但在昏暗的燈光下卻無法發揮作用。
When it gets dark the cones lose their ability to respond to light. The rods continue to respond to available light, but since they cannot see color, so to speak, everything appears to be various shades of black and white and gray.
當光線變暗時，錐狀體失去對光線做出反應的能力。而桿狀體繼續對光線做出反應，但由于它不能幫助人們識別顏色，因此所有的物體看上去都是不同形狀的黑色、白色或者灰色。
A curious thing is that in dim light you can see more clearly out of the side of your eye, because the light-sensitive rods are more highly concentrated off to the side in the back of your eye.
奇特的是，在光線暗淡情況下，通過眼睛兩邊的余光你能看得更清晰，因為桿狀體更集中地分布在眼睛后部的邊側。
So, next time you're out on a clear night, notice how little color you can see, and how you can see objects like dim stars better out of the corner of your eye than from the center.
所以，下次在一個晴朗的夜晚外出，留意一下你是不是看不見什么顏色，并且關注一下用眼角的余光看東西，例如晦暗的星星，會不會比正視看效果更好。
