英语听力：探索发现 科学新发现：我们的大气层-8

 Our planet was spared this fate. The magnetic field generated by the Earth’s core blocked the solar wind, preventing it from blasting away the fragile air. But the Earth’s atmosphere was still very different from the one we breathe today. It contained high level of carbon dioxide, a chemical with a key ability to absorb and hold on to heat. Carbon dioxide still makes up 95 percent of Venus’ atmosphere. It superheated our twin planet to the point where its water boiled away into space. And yet this didn’t happen on Earth. 

 

David crisp believes that was down to a chance event.

 

If Earth kept all of its initial atmosphere, it probably would have turned out a lot more like Venus. But that didn’t happen. We were victims of a very lucky accident. 

 

Earth’s big break came four and a half billion years ago. Back then, the solar system wasn’t limited to the 8 planets it has today. Instead, a swarm¹ of proto-planets or planetesimals orbited the sun like bees around a honey pot. One Mars-sized body was heading straight for Earth. In a colossal² cosmic collision, it slammed into our planet, creating our moon and according to Crisp, removing the atmosphere that still blights³ Venus. This ancient event was defining moment for our atmosphere. With the original deadly gas mix blasted away, our planet’s air could slowly evolve into what it is today.

1 swarm   

n.(昆虫)等一大群；vi.成群飞舞；蜂拥而入

参考例句：

• There is a swarm of bees in the tree.这树上有一窝蜜蜂。
• A swarm of ants are moving busily.一群蚂蚁正在忙碌地搬家。

2 colossal   

adj.异常的，庞大的

参考例句：

• There has been a colossal waste of public money.一直存在巨大的公款浪费。
• Some of the tall buildings in that city are colossal.那座城市里的一些高层建筑很庞大。

3 blights   

使凋萎( blight的第三人称单数 )； 使颓丧； 损害； 妨害

参考例句：

• The crops suffered from frequent blights. 农作物经常遭受病虫害。
• New England was accustomed to didacticism in its literature, and unmitigated didacticism blights the novel. 新英格兰习惯于在文学里说教，可是一味说教，小说就要完蛋。