SSS 2011-07-05
时间：2019-01-08 作者：英语课 分类：Scientific American(七)月
英语课
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 debris 1 called the solar nebula 2. The sun came first and the planets followed not long after.
But the new study shows that the ratio of oxygen and nitrogen isotopes 4 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 isotope 3 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.
n.瓦砾堆，废墟，碎片
- 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。
n.星云，喷雾剂
- 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。
n.同位素
- 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？