This is because their colors are not bright enough to be noticed by the human eye.
这是因为它们的颜色不够明亮，无法被人眼注意到。
Moonbows appear on the opposite side of the moon and usually look white to the human eye.
月虹出现在月亮的另一侧，它们在人眼中通常看起来是白色的。
Plants are also able to distinguish between specific wavelengths of light that the human eye cannot even see!
植物还能分辨出人类肉眼看不到的特定波长的光！
The human eye can detect more than 10, 000, 000 different colors!
人类的眼睛可以分辨超过10 000 000种不同的颜色。
To the human eye, orange is a very hot color, so it gives the sensation of heat.
在人眼看来，橙色是热力四射的颜色，因此它给人以热的感觉。
Today, telescopes take pictures using forms of light hidden from the human eye.
今天的望远镜使用一种肉眼无法看到的光线拍摄图片。
Motion Shots - Shoot subjects that move to fast for the human eye to follow and see clearly.
动作拍摄-拍摄那些对于人眼而言移动太快而难以跟随或者看清楚的物体。
These changes, imperceptible to the human eye, occur as the heart pumps blood through the body.
这些人类眼睛无法知觉的变化发生在心脏将血液泵向全身的时候。
A third contributor, who came closer to the majority view, said: "Ah, the human eye can be tricked so easily."
另一位网友的观点则代表了大多数人的看法：“人类的眼睛总是容易被骗。”
Indeed, the theoretical maximum gamut of a laser-based system is almost 90% of what the human eye can perceive.
确实，激光系统的最大色域理论上可以接近人眼能感知范围的90%。
The human eye is a highly non-linear device, and web-users can instantly recognize edges, patterns and motions .
人类的眼睛是一个高度非线性运作的设备，网页用户能够直觉地识别边界、模式和运动。
And when, Sirs, this pale flame has sprung into the air swaying to every wind, it brings vision to the human eye.
先生们，当这簇微弱的火焰在空气中绽放、随风摇曳时，它为人类的眼睛带来了景象。
Although the microscopic creatures look beautiful in photographs, many are not even visible to the human eye.
尽管这些显微生物在照片上是多么的美丽，但很多仅用肉眼却不可见到。
Of all the eyes in the animal kingdom, the human eye isn't the most efficient but it is still amazingly adaptable.
与动物王国中所有动物们的眼睛比起来，人类的眼睛并不是最高效的，但却具有令人惊叹的适应性。
The stars that the human eye can distinguish in the night sky are relatively near and are all part of the Milky Way.
夜空中人眼可以分辨的星星离我们相对较近，它们都是银河的组成部分。
The human eye reacts differently to a computer screen than a piece of paper, so how you format your e-mail is vital.
人眼对电脑屏幕和纸张的反应不同，所以如何安排电邮的格式非常重要。
Three new genetic loci have been identified with involvement in subtle and quantitative variation of human eye colour.
三种新的基因位点与人眼颜色的微小及定量变化有关。
"Looking up at the Moon, its surface appears painted with shades of grey, at least to the human eye," explained Robinson.
“抬头仰望月球时，人类的肉眼至少会看到月球表面呈深浅不一的灰色，”罗宾逊解释道。
The Firefox (browser) can see things that the human eye can't, too, but a lot of it doesn't get used for anything. So far.
火狐（Firefox）浏览器也可以看到人们看不到的东西，但迄今为止，这些东西还没有得到利用。
The human eye is incredibly good at recognizing complex behavior and spotting trends and patterns in visually displayed data.
在直观显示数据时，人类的眼睛在识别复杂的行为、运动轨迹和图案时表现得出奇地好。
If the interruption lasts for a few milliseconds, it is usually not noticeable to the human eye, ensuring operational continuity.
如果中断只持续几毫秒时间，那么这通常不会被肉眼所识别，这样运营持续性也仍然能够保证。
Just like the human eye Smart Eyes is able to distinguish different objects, even if they are moving on front of a busy background.
像人眼一样，电子眼能够辨别不同的物体，即使它们在一个杂乱的背景下移动。
Now scientists have tested a new method for monitoring the health of vegetation by measuring emissions that the human eye cannot detect.
如今，科学家试验了一种新的方法，通过测量人类肉眼观测不到的植被释放物质，监测其健康状况。
When shorter wavelengths of light, invisible to the human eye, hit the gold nanoparticles, they get excited and start to glow violet.
当金色纳米微粒收到肉眼不可见的更短波长的光照射时，它们将被激发并发出紫光。
SWIR technology detects reflected light at wavelengths that the human eye cannot see, in wavelength bands between visible and thermal cameras.
短波红外成像技术可以探测到可见光与热像仪波段之间人眼无法看到的反射光波长。
The light perceived by the human eye is measured in units called lumen-hours. This is about the amount produced by burning a candle for an hour.
人眼感受的光用流明时这个单位来衡量——燃烧一根蜡烛一个小时所产生的光的量就是一流明时。
Most of the invisibility cloaks that have been demonstrated to date conceal objects at frequencies that are not detectable by the human eye.
大部分隐身斗篷都是在非可见光波段隐藏物体。
These images can be used for threat analysis on the ground and on buildings, by detecting and showing changes not readily apparent to the human eye.
通过探测显示肉眼很难识别的变化，这些图像可用于分析地面和建筑物的威胁状况。
For instance, the picture quality on televisions is generally so good these days that many new advances are "not even perceptible to the human eye, " Bailey says.
例如现在的电视图像质量通常已经很好以至许多新的改进“让人们用肉眼察觉不到变化，”Bailey说。
Even the best liquid-crystal display (LCD) can produce only about a third of the range of colours which the human eye (in collaboration with the brain) can perceive.
即使现在最好的液晶显示屏,其产生的色彩数量也只能达到人眼（与人脑合作）色彩感知范围的三分之一。
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