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SSS 2011-07-05

时间:2011-08-09 03:22来源:互联网 提供网友:gmeng   字体: [ ]
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    (单词翻译:双击或拖选)

 This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will just take a minute.

 
If you’ve ever wondered where the Earth came from, the answer, it seems, is blowin’ in the wind—the solar wind. Or so say scientists who, after examining solar wind samples collected by the Genesis spacecraft, conclude that the inner planets of our solar system formed a little differently than we’d thought. The work appears in the journal Science. 
 
Our solar system arose from a large, rotating cloud of interstellar debris1 called the solar nebula2. The sun came first and the planets followed not long after.
 
But the new study shows that the ratio of oxygen and nitrogen isotopes4 found in the solar wind is different from the ratio here on earth, or on the moon or Mars. We’ve got more of the heavier versions of these atoms than our Sun does.
 
Now we just have to figure out why. Scientists say the excess heavy nitrogen could have come from a comet. And the heavier oxygen from a natural process that left more of the light isotope3 in the part of the nebula that made the sun. So we are made of star stuff. But when it comes to our elemental composition, we’re not a carbon copy.
 
Thanks for the minute. For Scientific American’s 60-Second Science, I’m Karen Hopkin.

点击收听单词发音收听单词发音  

1 debris 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。
2 nebula E55zw     
n.星云,喷雾剂
参考例句:
  • A powerful telescope can resolve a nebula into stars.一架高性能的望远镜能从星云中分辨出星球来。
  • A nebula is really a discrete mass of innumerous stars.一团星云实际上是无数星体不连续的集合体。
3 isotope isotope     
n.同位素
参考例句:
  • The isotope ratio is directly used for comparing oils or gases.同位素比率直接用于比较各种石油或天然气。
  • How to apply a radio isotope?如何运用放射性同位素?
4 isotopes 92848c3160703e48dc3b552ac6f54115     
n.同位素;同位素( isotope的名词复数 )
参考例句:
  • the many isotopes of carbon 碳的诸多同位素
  • Tritium is one of the mildest radioactive isotopes. 氚是最和缓的放射性同位素之一。 来自《简明英汉词典》
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