今天要和各位小伙伴介绍的是托福听力题型之天文类lecture，有需求的朋友可以看一看文章内容哦，希望这些内容能够帮助到大家!
天文学这门自然科学的课程，相对来说是非常具有学科特色的，与一些人文科学类的内容有所不同，人文科学类在日常生活或者平时积累中就可以获取一些背景知识，但天文学不是刻意了解的话肯定是不知道的。
所以，相较而言，了解天文学的常考背景就变得非常重要。大家平时可以多看看像NASA出的一些介绍片，或者BBC里一些关于天文的纪录片。你会发现，对天文越深入的了解和学习，你会越喜欢这类学科带来的魅力。
天文学常考学科范围一：各种星系相关
在整个太阳系中，行星根据组成成分不同分成两类：
The terrestrial planets(类地行星)--like Mars and Earth(火星和地球)--composed largely of rocks and metals(由大多数的岩石以及金属组成), and the large gas giants(类木行星), like Jupiter(木星). Well, the solar system also has two analogous classes of objects, smaller than planets--namely, asteroids and comets(彗星和小行星是行星的类似物，只是相对来说体积较小).
Both comets and asteroids are...typically are smaller than planets(彗星和小行星体要比行星来的小). And even smaller type of interplanetary debris is the meteoroid. And it's from meteoroids that we get meteors and meteorites(流星体是一种更小的东西，流星和陨石也是由此得来的). When these bits enter earth’s atmosphere, well, that makes them so special that they get a special name. They're called meteors(进入大气层的称之为流星).Most of them are very small, and they burn up soon after entering earth’s atmosphere. The larger ones that make it through the atmosphere and hit the ground are called meteorites(经历燃烧等掉入大地的叫做陨石).
天文学常考学科范围二：外太空各种星系是否有生命存在
首先，从科学角度出发，只有一些类地行星(terrestrial planet)上才可能适宜生命存在，一般常考的是火星上是否有生命迹象存在。尤其是一些微生物的发现，使得人们非常好奇火星上是否有生命存在。
文中考到的内容Jarosite(黄钾铁矾)is a yellowish brown mineral with a crystalline structure(晶状体结构) that’s also found on Earth. It contains iron, potassium and hydroxide(含铁，钾，氢氧化物). The interesting thing is that on Earth at least it needs highly acidic water to form(需要强酸性的水). So we’ve got water or had it at one point(所以能证明水的存在)……But Jarosite on Earth incorporates all kinds of microorganisms into its crystalline structure. So it’s possible that if the Jarosite on Mars was also formed with the help of microorganisms(还有可能微生物也起到了一定的作用).
天文学常考学科范围三：光谱技术
Spectroscopy is the study of the interaction between matter and light(光谱研究物质和光之间的关系，大多时候的光谱都是一些星星发出的光). Now, visible light consists of different colors or wavelengths, which together make up what's called spectrum, a band of colors, like you see in a rainbow. And all substances, all forms of matter, can be distinguished according to what wavelength of light they absorb and which ones they reflect. It's like, um, well, every element has, what we call, its own spectral signature(不同的颜色代表不同的化学组成成分). If we can read that signature, we can identify the element. And that's exactly what spectroscopy does(而这个技术通常用于艺术发展史中的艺术品修复技术).
天文学常考学科范围四：天文学实际应用
Polynesians was to look for a star pair, that’s two stars that rise at the same time, or set at the same time, and navigators could use these pairs of stars as reference points, because they rise or set together only at specific latitudes(一对星星在某个相同的纬度同起同落). So navigators might see one star pair setting together. And, uh…would know how far north or south of the equator they were. And if they kept on going, and the next night they saw the pairs of stars setting separately, then they would know that they were at a different degree of latitude(航海家通过辨别星星的纬度来辨别位置航海方向), so looking at rising and setting star pairs is a good technique.
如果感觉上面的一些专业背景知识比较晦涩，那说明我们需要好好的沉下心来去学习，天文学中很多文章的本身就很有故事特色，如果研究到位，会发现每一篇天文学都是一个伟大故事的呈现。
以上就是要和各位朋友介绍的托福听力题型之天文类lecture，希望这篇文章能够对大家的学习有所帮助!
