根据海阔天空0822童鞋提供的JJ找到的悦读JJ背景知识，很相似哦~

nancy716

文章来自NASA
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Where did the Moon come from?

                              

Answer:

Any theory which explains the existence ofthe Moon must naturally explain the following facts:

• The Moon's low density     (3.3 g/cc) shows that it does not have a substantial iron core like the     Earth does.
  
• Moon rocks contain few volatile substances (e.g. water), which     implies extra baking of the lunar surface relative to that of Earth.
  
• The relative abundance of oxygen isotopes on Earth and on the     Moon are identical, which suggests that the Earth and Moon formed at the     same distance from the Sun.
  

Various theories had been proposed for theformation of the Moon. Below these theories are listed along with the reasonsthey have since been discounted.

• The Fission Theory(裂变理论): This theory proposes that the Moon was once part of the Earth     and somehow separated from the Earth early in the history of the solar     system. The present Pacific Ocean basin is the most popular     site for the part of the Earth from which the Moon came. This theory was     thought possible since the Moon's composition resembles that of the     Earth's mantle     and a rapidly spinning Earth could have cast off the Moon from its outer     layers. However, the present-day Earth-Moon system should contain     "fossil evidence" of this rapid spin and it does not. Also, this     hypothesis does not have a natural explanation for the extra baking the     lunar material has received.
  

认为月球是从地球分裂出去的。

原因：月球的构成与地幔相似；地球自转可以把月球从地球外层甩出去。

评价--不太可能：现在的地月系统对于月球被甩出去的这一理论没有化石证据；也没有月球物质受到baking的自然证据

• The Capture Theory（俘获理论） This     theory proposes that the Moon was formed somewhere else in the solar     system, and was later captured by the gravitational     field of th
  

starlitcream

Thx for sharing

448406078

DDD

700++++++++++

Waterlady

Many many thanks!

kiko492

谢谢~~~~~~~~~~····