柯灵思英语-英语听力高手36

As regards the origin of life on earth, we used to believe that when life began on earth, the atmosphere contained nitrogen, hydrogen and other gases but no oxygen. Consequently, the sun's rays prevented life from developing on land. That explained why the first living organisms developed only under the sea. Under the influence of photosynthesis¹, the oxygen in the atmosphere increased and life expanded. Complex living organisms developed. As the oxygen in the atmosphere increased, life, which depends on the equilibrium² of the atmosphere, was possible on the surface of the earth.

Recently, we have come up with a very different hypothesis. We believe that hundreds of millions of years ago, a meteor crashed into a then-lifeless planet. Embedded³ in the meteor were carbon compounds that were to become the seeds of all life on earth. Our current hypothesis is that there was a seeding from elsewhere. Let's say a meteor that had originated in Mars landed in the Antarctic, and it contained evidence of life.

Last month, we observed the Leonid meteor showers, which occur in every November when Earth passes through the debris⁴ shed by the comet Tempel-Tuttle. We were aboard two U.S. Air Force craft that flew at night from the United Kingdom to Israel, then back through the Azores to Florida. The path allowed us to observe the meteors - some no bigger than a grain of sand - from an altitude of 11-and-a-half kilometers. Images of the meteors were fed through infrared⁵ spectrographic-instruments that can detect the unique chemical fingerprints⁶ of complex organic molecules⁷ of the type that may have"seeded" life on earth. Our spectrographic instruments caught a meteor "in the act" of disseminating⁸ organic molecules.

We have a list of perhaps 100 carbon-containing compounds that have been identified. These are the building blocks of life. We use the term "pre-biotic life" to describe them. So that is a major interest of astrobiology - to search for the chemicals that exist in the universe outside of earth that could lead to life, probably in some sort of continuous process.

1 photosynthesis   

n.光合作用

参考例句：

• In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。
• Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

2 equilibrium   

n.平衡，均衡，相称，均势，平静

参考例句：

• Change in the world around us disturbs our inner equilibrium.我们周围世界的变化扰乱了我们内心的平静。
• This is best expressed in the form of an equilibrium constant.这最好用平衡常数的形式来表示。

3 embedded   

a.扎牢的

参考例句：

• an operation to remove glass that was embedded in his leg 取出扎入他腿部玻璃的手术
• He has embedded his name in the minds of millions of people. 他的名字铭刻在数百万人民心中。

4 debris   

n.瓦砾堆，废墟，碎片

参考例句：

• After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
• Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上，导致蛀牙。

5 infrared   

adj./n.红外线(的)

参考例句：

• Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
• Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。

6 fingerprints   

n.指纹( fingerprint的名词复数 )v.指纹( fingerprint的第三人称单数 )

参考例句：

• Everyone's fingerprints are unique. 每个人的指纹都是独一无二的。
• They wore gloves so as not to leave any fingerprints behind (them). 他们戴着手套，以免留下指纹。 来自《简明英汉词典》

7 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

8 disseminating   

散布，传播( disseminate的现在分词 )

参考例句：

• Our comrades in propaganda work have the task of disseminating Marxism. 我们作宣传工作的同志有一个宣传马克思主义的任务。
• Disseminating indecent photographs on the internet a distasteful act. 在因特网上发布不雅照片是卑劣的行径。