Learn all about the human eye…
瞭解人眼
You carry around a pair of cameras in your head so incredible they can work in bright sunshine or at night. Only 2.5cm in diameter, they can bring you the image of a tiny ant or a twinkling star trillions of kilometres away. They can change focus almost instantly and stay focused even when you're shaking your head around. These cameras are your eyes…
你頭上帶著一對照相機，這樣它們就可以在明亮的陽光下或夜晚工作了。直徑只有2.5釐米，它們能給你帶來數萬億公里外的一隻小螞蟻或一顆閃爍的恆星的影像。它們幾乎可以立即改變焦點，即使你搖頭也能保持注意力集中。這些相機是你的眼睛。
Eye-Popping Fact ONE: A crucial part of your eyes is as flimsy as a wet tissue!
令人瞠目結舌的事實一：你眼睛的關鍵部位就像溼紙巾一樣脆弱！
A fly darts towards your head! Light bounces off the insect and enters your eye's cornea, a clear covering over your eye. The light passes through your pupil, the black circle in the centre of the iris, to the lens. The lens focuses the light onto your retina – a thin but vital lining on the back of your eye that is as flimsy as a wet tissue. Your retina acts like camera film, capturing the picture of the fly. This image is sent to the brain, which instantly tells you to – duck!
一隻蒼蠅飛向你的頭！光線從昆蟲身上反射，進入你的眼角膜，一個覆蓋在你眼睛上的透明物。光線通過你的瞳孔，虹膜中心的黑色圓圈，到達鏡頭。晶狀體將光線聚焦到視網膜上，視網膜是你眼睛後部一層薄而重要的內層，薄如溼組織。你的視網膜就像照相機的膠片，捕捉蒼蠅的照片。這張圖片被髮送到大腦，大腦會立即告訴你-鴨子！
Eye-Popping Fact TWO: You blink more than 10,000 times a day!
令人瞠目結舌的事實二：你每天眨眼超過一萬次！
Your sight is incredibly important , so your body has ways to protect your eyes. Each eye sits on a cushion of fat, surrounded by protective bone. Your eyebrows prevent sweat dripping into your eyes, while eyelashes keep dust and other particles out. The eyelids act as windscreen wipers, spreading tear fluid with every blink to keep your eyes moist and wash away bacteria. You blink more than 10,000 times a day! And if anything gets too close, your eyelids slam shut with amazing speed. How fast does this happen? In the blink of an eye – about 2/5 of a second!
你的視力非常重要，所以你的身體有辦法保護你的眼睛。每隻眼睛都坐在脂肪墊上，周圍有保護性的骨頭。你的眉毛可以防止汗水滴入眼睛，而睫毛可以防止灰塵和其他微粒進入眼睛。眼瞼起著擋風玻璃雨刷的作用，每眨眼一眨眼，都會散開淚液，保持眼睛溼潤，洗去細菌。你每天眨眼超過10000次！如果有什麼東西靠得太近，你的眼皮會以驚人的速度猛地閉上。這種情況發生得有多快？一眨眼之間——大約2/5秒！
Eye-popping Fact THREE: Your eyes adjust in milliseconds to ANY movement of your head!
令人瞠目結舌的事實三：你的眼睛可以在幾毫秒內適應你頭部的任何運動！
You bounce your eyes around all the time. Even when you're not running or jumping, your head doesn't stay still. Why isn"t everything a blur when you"re moving? The eyes automatically adjust to the movement of your head with great speed and precision. They're good at following a moving object, and even better at adjusting to the motion of your head. Test it: Keeping your head still, hold up your hand about 30cm away, and quickly move it back and forth. As fast as your eyes are, your fingers become blurry. Now keep your hand still and move your head back and forth. Amazingly, your fingers stay in focus!
你的眼睛一直在跳動。即使你沒有跑步或跳躍，你的頭也不會保持靜止。為什麼你搬家的時候一切都不模糊？眼睛會自動適應你頭部的運動，速度和精度都很高。他們善於跟蹤移動的物體，甚至能更好地適應你的頭部運動。測試：保持頭部靜止，將手舉離30釐米左右，快速前後移動。你的眼睛越快，手指就越模糊。現在手不要動，頭要前後移動。令人驚訝的是，你的手指保持專注！
Eye-Popping Fact FOUR: Your eyes see everything upside down and backward!
令人瞠目結舌的事實四：你的眼睛看到所有東西上下顛倒！
Your eyes are amazing, but the images they send to your brain are a little quirky – they're upside down, backward and two-dimensional! Lucky for you, the cameras in your head come with an impressive software package – your brain – that can fix these problems. The brain automatically flips the images from your retinas right side up and combines the images from each eye into a three-dimensional picture.
There is a small area of each retina, called a blind spot, that can't record what you're seeing. Your brain makes adjustments for this, too. But sometimes it can be fooled! Check it out – hold the tips of your two index fingers together, about 15cm in front of your eyes. Now separate them slightly and look past them at something in the distance. A floating finger that looks like a sausage appears between your fingers. You just fooled your brain into seeing something that isn't there!
你的眼睛是驚人的，但他們發送到你的大腦的圖像是有點古怪-他們顛倒，向後和二維！幸運的是，你腦袋裡的攝像頭有一個令人印象深刻的軟件包——你的大腦——可以解決這些問題。大腦會自動將視網膜上的圖像向上翻轉，並將每隻眼睛的圖像組合成三維圖像。
每個視網膜上都有一小塊區域，叫做盲點，不能記錄你看到的東西。你的大腦也會對此做出調整。但有時它會被愚弄！檢查一下-把兩個食指的指尖放在一起，大約在眼睛前面15釐米。現在把它們稍微分開，然後從它們旁邊看遠處的東西。一個看起來像香腸的漂浮手指出現在你的手指之間。你只是愚弄了你的大腦去看不存在的東西！
Eye-Popping Fact FIVE! Your pupils change size whenever the light changes!
令人瞠目結舌的事實五！只要光線改變，你的瞳孔就會變大！
Your black pupils may be small but they have an important job – they grow or shrink to allow just the right amount of light to enter your eyes to let you see. Try this: Go into a windowless room, turn off the light and close the door so there is just enough light to see the pupils in your eyes in the mirror. Your pupils will be far larger than usual, having grown to their maximum size to capture as much light as possible. Now, turn on the light while still watching your pupils. You'll see them shrink to a small dot almost immediately – right before your very, um…eyes!
你的黑瞳孔可能很小，但他們有一個重要的工作-他們成長或縮小，以允許恰到好處的光線進入你的眼睛，讓你看到。試試這個：走進一個沒有窗戶的房間，關上燈，關上門，這樣就有足夠的光線在鏡子裡看到你眼中的瞳孔。你的瞳孔將比平時大得多，已經長到最大尺寸以儘可能多地捕捉光線。現在，在看學生的時候把燈打開。你會看到它們幾乎立刻縮小成一個小點-就在你的眼睛前面，嗯…眼睛！
