Basic answers to some basic questions:一些基本问题的基本答案：
Sky 天空
The sky appears blue because as white light shines on Earth from the sun gas molecules in the Earth's atmosphere absorb the “blue” part of the visible electromagnetic spectrum.天空呈蓝色，因为地球上的白光照射从地球大气的气体分子吸收太阳“蓝”的电磁频谱的可见部分。 [1] [1] These molecules then radiate the blue light into the sky in a process known as the Rayleigh scattering.这些分子然后辐射到天空中的瑞利散射过程叫做蓝灯。 Our eyes see the scattered light and the sky appears blue.我们的眼睛看到的散射光，天空呈蓝色。 [2] [2] Atmospheric gas molecules do not absorb other parts of the electromagnetic spectrum (red, yellow etc) to the same degree and we therefore rarely see those colors in the sky.大气气体分子不吸收电磁波谱的其他部分（红色，黄色等），以同样的程度，因此，我们很少看到在天空的颜色。
Grass 草
The grass appears green because plants contain a chemical called chlorophyll, essential to photosynthesis.草绿色的出现，因为植物含有的化学物质称为叶绿素，光合作用必不可少的。 Chlorophyll absorbs all parts of the visible spectrum of light except the wavelengths corresponding to the color green.除了叶绿素吸收波长相对应的，绿色的所有可见光光谱部分。 Chlorophyll reflects the green light and as long as grass contains chlorophyll it will look green to us.叶绿素反映了绿灯，只要草含有叶绿素它的外观给我们的绿色。 [3] [3]
Sun 太阳
The sun appears yellow because of the Rayleigh scattering: the light that eventually reaches our eyes from the sun on the surface of the Earth is predominately the “yellow” & “red” portions of the electromagnetic spectrum. In addition, the temperature of the surface of the sun happens to produce a spectrum of visible light where yellow is most plentiful (but if the Rayleigh scattering did not exist both the sky & the sun would look very different to us).太阳出现黄色由于瑞利散射：轻，最终到达了对地球表面的太阳我们的眼睛，是为主的“黄色”和“红色”电磁频谱的部分。此外，表面温度太阳的发生产生的可见光光谱其中黄色是最丰富的（但如果瑞利散射双方不存在天空和太阳看起来对我们非常不同）。
Basically whatever color you see is the part of the visible electromagnetic spectrum that is not absorbed by the material, object, or area in question.基本上任何颜色你看到的是可见的电磁频谱不是由原材料，对象，或有关地区吸收的一部分。 [4] [4]
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A good comment from reddit that gets even deeper into things:来自reddit的事情就会更深入到好评论：
“Again, though these answers are correct, the deeper explanations are yet more interesting, and even simpler… “而且，尽管这些答案是正确的，深刻的解释感到更有趣，更简单...
1) Sky is blue – thinness of the atmosphere allows only the very highest energy wavelengths to be scattered, while the lower energy wavelengths can endure the transit through the atmosphere to our eyes. 1）天是蓝的-大气薄只允许极高能量波长分散，而低能量的波长可以承受，通过我们的眼睛气氛过境。 Evenings and mornings are colored, as the light must travel a longer distance through the absorbing atmosphere – and thus lower and lower wavelengths get scattered.晚上和早上的颜色，因为光必须穿过大气层吸收较长的距离-因而低，波长得到分散。
2) Grass is green because it absorbs other wavelenghts, but interestingly it is tuned evolutionarily to be as maximally efficient in absorbing light from our sun as possible. 2）草是绿色的，因为它吸收了其他wavelenghts，但有趣的是调整进化作为最大限度地从我们在吸收阳光尽可能高效。 The green color comes as a side effect of absorbing the most highly energetic light coming from the sun.绿色的颜色来作为吸收最高能量吸收太阳光，未来的副作用。 Change the energetic maximum from the sun, and plants colors would change to match it.更改来自太阳活力最大，植物的颜色会改变与之相匹配的。
3) The highest energy light coming from the sun (that the green plants absorb) is directly related to the emission from the particular elements that make up the sun. 3）最高能量吸收太阳光来（即绿色的植物吸收），是直接关系到从特殊元素的排放，使出太阳。 Dependent upon the size and composition of the sun (percent Hydrogen, helium, etc.) the emission spectra will be of a particular color.的大小和太阳的组成（百分之氢，氦等）的发射光谱依赖将是一种特定的颜色。
These three are all tied to basic physical processes.这三个都依赖于基本的物理过程。 The sun emits its color from electrons jumping from very particular heights based on the elements in the sun.太阳发出的从阳光中的元素为基础的非常特殊的跳楼电子，它的颜色。 The sky is the color it is because of how the atmosphere absorbs the sun's emissions.天空的颜色，是因为大气层如何吸收太阳的排放量。 And the plants are the color they are in order to maximize energy absorption of the sun's light that reaches them through our atmosphere.”而植物的颜色，他们是为了最大限度地提高能源的太阳光线经过我们的大气层到达它们的吸收。“
See:见：
http://www.reddit.com/r/science/comments/8vz3u/why_the_sky_is_blue_the_grass_green_the_sun_yellow/ http://www.reddit.com/r/science/comments/8vz3u/why_the_sky_is_blue_the_grass_green_the_sun_yellow/