在2014年5月11日的托福阅读考试中有这样一道题：如何判断地质年龄。针对这道托福考题，出国留学网(www.liuxue86.com)小编来为大家普及一下关于地质年龄的背景知识，这样有助于考生在面对这类题目时方便作答。小编在此提醒大家：天文主题文章的词汇专业性较强，需要提前对相关专题的TPO文章的生词熟悉，尽量减少生词恐惧带来的内耗。
托福阅读真题再现：
版本1:
文章先讲太阳系里的东西都有相同的起源。先是说所有的东西是在一起的，然后说地球由于地表的水、火山活动和一个什么过程使得地球连最古老的石头都没有了。所以只能测定月球的陨石的成分了，结论是月球的表面和陨石的时间都是46亿年。因为月球表面没有地球的这些活动，所以可以测定。
后面又说宇宙的星系都在不断地拉开距离，通过星系的红移可以确定距离还有速度，发现宇宙一直在膨胀。发现宇宙在137亿年前是一个点。然后就有了宇宙大爆炸。
版本2： 讲地球和宇宙年龄的测量。先说太阳系大部分物质是同一时间形成的，然后说地球年龄难是因为谁腐蚀。接着引入一种物质，可以通过同位素测年龄。结果是和月球上的最古老的石头近似。然后说宇宙在膨胀，大爆炸。通过红移测年龄。
版本3： 天文类， 某种地球上的物质和月球上最古老的物质证明他。都始于自4.6million年前，于是证明太阳系的年龄是4.6 Million years. 另外还有种通过判断各星球一种wavelength的大小推断出他们在多少年前都是从个spot发展出来，于是判断了big bang的时间。
托福阅读相关词汇：
origin 起源
meteorite 陨石
galaxy 星系
expansion 膨胀
red shift 红移
wavelength 波长
解析：
天文主题文章的词汇专业性较强，需要提前对相关专题的TPO文章的生词熟悉，尽量减少生词恐惧带来的内耗。另外，出现天文理论的文章，结构通常都会比较清晰，但要着重识别对理论内容的态度倾向。
托福阅读相关背景：
a.Big Bang
The Big Bang theory is the prevailing cosmological model for the early development of the universe. According to the theory, the Big Bang occurred approximately 13.82 billion years ago, which is thus considered the age of the universe. At this time, the universe was in an extremely hot and dense state and was expanding rapidly. After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, including protons, neutrons, and electrons. Though simple atomic nuclei formed within the first three minutes after the Big Bang, thousands of years passed before the first electrically neutral atoms formed. The majority of atoms that were produced by the Big Bang are hydrogen, along with helium and traces of lithium. Giant clouds of these primordial elements later coalesced through gravity to form stars and galaxies, and the heavier elements were synthesized either within stars or during supernovae.
b.Accelerating universe
The accelerating universe is the observation that the universe appears to be expanding at an increasing rate. In formal terms, this means that the cosmic scale factor has a positive second derivative,[1] so that the velocity at which a distant galaxy is receding from us should be continuously increasing with time.[2] In 1998, observations of type Ia supernovae also suggested that the expansion of the universe has been accelerating[3][4] since around redshift of z~0.5.[5] The 2006 Shaw Prize in Astronomy and the 2011 Nobel Prize in Physics were both awarded to Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess, who in 1998 as leaders of the Supernova Cosmology Project (Perlmutter) and the High-Z Supernova Search Team (Schmidt and Riess) discovered the accelerating expansion of the Universe through observations of distant ("High-Z") supernovae.[6][7]
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