2011年考研優(yōu)美英語作文背誦045

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    The Source of Energy

    A summary of the physical and chemical nature of life must begin， not on the Earth， but in the Sun； in fact， at the Sun's very center. It is here that is to be found the source of the energy that the Sun constantly pours out into space as light and heat. This energy is liberated at the center of the Sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium， and in doing so， release some of the energy that is stored in the nuclei of atoms. The output of light and heat of the Sun requires that some 600  million tons of hydrogen be  converted into  helium in the Sun every second.  This the Sun has  been  doing for several thousands  of  millions of years.  The nuclear energy is released at the Sun's center as high-energy  gamma radiation， a form of electromagnetic radiation like  light and radio waves， only of very much shorter wavelength. This gamma radiation is absorbed by atoms inside the Sun to be reemitted at slightly longer wavelengths. This radiation，  in its turn is  absorbed  and reemitted. As the energy filters through the layers of the solar interior， it passes through the X-ray part of the  spectrum eventually becoming light. At this stage， it has reached what we call the solar surface， and can escape into space without being absorbed further by solar atoms. A very small  fraction  of  the  Sun's  light  and  heat  is    emitted  in  such  directions  that  after  passing unhindered through interplanetary space， it hits the Earth.

    全文翻譯：能量的來源

    概說生命的物理和化學(xué)特性必須始于太陽——確切地說，是太陽的核心，而非地球。  能 量來自太陽的核心。 在這里，太陽不停地以光和熱的形式向空間傾瀉出能量。 數(shù)十億計(jì)的 氫原子核在太陽的核心碰撞并且聚變生成氦。  在此過程中一部分原本儲存于原子核中的能 量被釋放出來。 太陽所產(chǎn)生的光和熱需要每秒將六億噸氫轉(zhuǎn)化為氦。 這樣的轉(zhuǎn)化在太陽中已經(jīng)持續(xù)幾十億年了。  核能在太陽的核心被釋放為高能的伽馬射線。  這是一種電磁射線， 就象光波和無線電波一樣，只是波長要短得多。這種伽瑪射線被太陽內(nèi)的原子所吸收，然 后重新釋放為波長稍長一些的光波。 這新的射線再次被吸收，而后釋放。 在能量由太陽內(nèi)部一層層滲透出來的過程中，它經(jīng)過了光譜中 X 射線部分，最后變成了光。  在此階段，能量到達(dá)我們所稱的太陽表層，并且離散到空間而不再被太陽原子所吸收。  只有很小一部分 太陽的光和熱由此方向釋放出來，并且未被阻擋，穿越星空，來到地球。