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"As Earth was being formed out of the collision of space rocks, the heat from those collisions and from the increasing gravitational energy of the planet made the entire planet molten, even the surface. Any water present would have evaporated and gone off into space.1 As the planet approached its current size, however, its gravitation became strong enough to hold gases and water vapor around it as an atmosphere.1 Because comets are largely ice made up of frozen water and gases, a comet striking Earth then would have vaporized. The resulting water vapor would have been retained in the atmosphere, eventually falling as rain on the cooled and solidified surface of Earth. Therefore, the water in Earth's oceans 2 must have originated from comets."
1 碰撞蒸发的水分(也就是彗星的水分)既然消失,那么随后从宇宙中吸收的水分就不是来自彗星了。或者一个来撞,其他很多也被这个热量融化(汗),但是没有证据说明一次撞击可以带来如此大的热量。
2 可能是一部分来自融化后的彗星,一部分来自宇宙中的其他水分被地球吸收?因为没有证据表明现存的彗星含水量能满足地球海洋的总水量要求。
正文:
The author gives us a conclusion about the form progress of Earth. He cites a theory in which the collision of space rocks may cause enough heat to melt the whole earth, then after it became to its current size, the water vapor around it would be gathered by its gravitation so as to hold an atmosphere. Since comets are made mainly of frozen water and gases, this argument attributes the water in Earth’s oceans to the collision of comets and Earth. All these hypothesis seem correct at the first glance, but in fact they can hardly hold water after careful consideration.
At first, the theory itself is contradicted with the arguer’s view. He fails to explain the puzzle that if any water present, which means the water contained in the collision comet, would have evaporated and gone off into space, how can this part of water be the oceans later? It is very possible that although a comet really collided Earth, the water in it all disappeared because of the melting caused by Earth’s gravitation, while water in oceans came from other methods though we lack enough evidences. Admittedly, there is no denying that perhaps one comet rushed into Earth so as to melt it and then another, or even more, comets were also melted by the heat of Earth so at last their vapors all left in this plant. However, without any information about whether the heat of Earth’s melting could deal with so many comets, we can hardly believe this oversimplified assumption.
At second, it may also be possible that some water of the collision comet were not far from the earth after the melting progress, so when this planet became to its current size it still attracted some of them as parts of its atmosphere. Anyway, there is a great chance for us to doubt that not all the water actually came from this way. This article ignores several other factors such as there may be vapors which evaporated into space from other planets, and accidentally be absorbed by Earth. Also the editorial fails to provide enough support that the water amount in oceans can meet the containments of frozen water and vapors in existed comets in space. Maybe all the comets’ water cannot satisfy the oceans need. Lacking more evidences that total quantity of water is contribution of comets, the conclusion is of little convincement.
Generally speaking, the author makes an insanity deduct with an oversimplified theory. In order to persuade his readers to believe him, he needs to do more research about the amount of water contained in comets and other possible channels of water into the earth to see whether all the water in oceans is the result of comets collision. |
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