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是原文吗？
第一段：虽然里面的原子atoms很多，但是其实dusts分布更广，而且性质还和原子有比较。dust比atoms更thinly，是spread, without uniformity,（考了一道对比题）。一个人发现dust才是影响星系亮度的原因。这种粒子会使我们在地球上观测到的星星比实际的暗而且红（考点问观测了什么）。因为这些dust会影响星星发出来的光，它会使星星的光的波长移动。
THE SPACE between the stars is not quite a perfect vacuum. A volume of space the size of a small matchbox would contain – on average – half a dozen atoms, mainly hydrogen. Spread much more thinly are the solid particles, which astronomers call dust grains. The gas and dust is spread out between the stars of our galaxy, the Milky Way, a vast Catherine wheel of 200 000 million stars (including the Sun), about 100 000 light years across. (A light year is the distance travelled by light in one year, 9.46 million million – 9.46 × 1012 – kilometres.)
Not all the dust is spread out uniformly. In places we find interstellar clouds. These are regions where the gas and dust in space concentrate into denser clumps. The dense concentration of dust blocks out virtually all the light from more distant stars, so the cloud appears as a dark silhouette.
ALTHOUGH the grains in interstellar space are microscopic and lie hundreds of light years away, astronomers have deduced a lot about them from their sizes and shapes, and even their composition.
然后说叫什么T的天文学家，他研究这个，确定了这个dust的大小。比如，红光的波动被shift，那dust的大小就和红光波长差不多，如果是蓝光的波长被shift，那大小就和蓝光的波长差不多。（大概是说科学家观测到星星通过某太空某处dust以后发生红移，就推断说那个地方dust的size应该在红色波和蓝色波之间等等。）
The first clue comes from examining the starlight that penetrates the general dust in space. In the 1920s, a Swiss astronomer, Robert Trumpler, discovered that stars lying behind interstellar dust not only appear dimmer, but are also slightly redder in colour than we would expect. He concluded that the dust grains were absorbing more of the shorter wavelengths (blue light) than the longer (red) wavelengths. So particles in the Earth’s atmosphere make the Sun look redder when it is low in the sky (its colour has nothing to do with the shift to red caused by moving bodies, the Doppler effect).
问举大海波浪的例子是什么目的
答案应该是做一个类比analogy/用来做analogy
原文大意是ocean wave遇到比自己小的石头，就不会被干扰，所以红色波长遇到比自己小的dust，也会不受干扰的过去
This discovery tells us the size of the dust grains. They must be smaller than the wavelength of red light (0.7 micrometres, where a micrometre is a thousandth of a millimetre), because the dust has relatively little effect on these wavelengths – just as an ocean wave is not affected if it encounters a protruding rock that is smaller than the distance between the wave-crests. But the grains must be comparable in size to the wavelength (0.4 micrometres) of the blue light that the dust affects more seriously.
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发表于 2018-9-26 17:32:41
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楼主能不能回忆一下作文呢？