英语听力：自然百科 穿越银河系的旅行 Through Milky Way—12

 We are at a foundry here, and they are pouring molten iron from all machinery¹. And they are going to make parts for new machines out of that iron, so they are recycling yet, but all that iron was created and ejected into the cosmos² by gigantic stars that exploded as supernovae. Those explosions created the iron and ejected into the cosmos, and then they got incorporated into planetary systems like ours, but ultimately the atoms of iron were created by exploding stars. Supernovae are the industrial zones of our star city, cosmic foundries in which the chemistry of the heavens forges new elements. 

 

 

 

It is fascinating to realize that the heavy elements in our bodies, the carbon in our cells, the calcium³ in our bones, the oxygen that we breathe, the iron in our red blood cells. All of those heavy elements were synthesized, created through nuclear reactions in star, and ejected into the cosmos by supernovae. 

 

 

 

Only some stars are massive enough to die as supernovae. Most, like our sun, suffer a more gentle death. Most stars don’t die in the cataclysmic explosion. Our own sun, for example, a typical star, will die with a whimper not a bang. 

 

 

 

The death of most stars occurs when the battle, between gravity pulling in and nuclear energy pushing out, is won, not by gravity but by the nuclear energy.

1 machinery   

n.(总称)机械，机器；机构

参考例句：

• Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗？
• Machinery ought to be well maintained all the time.机器应该随时注意维护。

2 cosmos   

n.宇宙；秩序，和谐

参考例句：

• Our world is but a small part of the cosmos.我们的世界仅仅是宇宙的一小部分而已。
• Is there any other intelligent life elsewhere in the cosmos?在宇宙的其他星球上还存在别的有智慧的生物吗？

3 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。