英语听力：自然百科 地球力场 Earth's Force Field—2

 Radiation causes damage at the most fundamental level. It mutates the blueprint¹ of life, DNA². Earth's magnetosphere is our crucial defense³. It's so fundamental to our evolution and continued existence that the race is on to understand why it's changing. Although scientists can peer millions of miles into space, they still can't see the Earth's magnetic field. 

 

NASA scientist Dr. Mario Acuna's simple demonstration⁴ helps us to visualize⁵ its basic structure. “We can use a real bar magnet to visualize what the magnetic field of the Earth may look like. So, we're gonna put this under this. 

 

It’s a cardboard here. And now we are going to sprinkle slowly, some iron filings. In school, we all play with iron filings and we sprinkle them on a bar magnet, then we see these lines that form, that go from North to the South. And that in a fact, basically describes the rough geometry of the Earth's magnetic field.”

 

So, just as iron filings arrange themselves, around the north and south poles of a bar magnet, the Earth's magnetic field spurts⁶ out like a fountain at the magnetic South Pole. It encircles the entire planet and streams back down into the Earth at the magnetic North Pole. 

 

Scientists believe it's generated 3000 miles beneath our feet, deep within the Earth's interior. From here, it throws out a vast magnetic cocoon⁷ that envelops⁸ the entire planet. This blocks out the solar wind, a constant barrage⁹ of superheated charged particles streaming from the Sun at up to a million miles per hour.

 

Professor Daniel Lathrop from the University of Maryland has seen how powerful the solar wind can be.

 

“Solar wind comes in and hits the bow shock on the magnetosphere, and tends to just go around them with whole thing shaped like a big tadpole¹⁰. Most of the radiation then ends up streaming  past the Earth. A little bit leaks in and hits the atmosphere near the Poles.”

 

1 blueprint   

n.蓝图，设计图，计划；vt.制成蓝图，计划

参考例句：

• All the machine parts on a blueprint must answer each other.设计图上所有的机器部件都应互相配合。
• The documents contain a blueprint for a nuclear device.文件内附有一张核装置的设计蓝图。

2 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

3 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

4 demonstration   

n.表明，示范，论证，示威

参考例句：

• His new book is a demonstration of his patriotism.他写的新书是他的爱国精神的证明。
• He gave a demonstration of the new technique then and there.他当场表演了这种新的操作方法。

5 visualize   

vt.使看得见，使具体化，想象，设想

参考例句：

• I remember meeting the man before but I can't visualize him.我记得以前见过那个人，但他的样子我想不起来了。
• She couldn't visualize flying through space.她无法想像在太空中飞行的景象。

6 spurts   

短暂而突然的活动或努力( spurt的名词复数 )； 突然奋起

参考例句：

• Great spurts of gas shoot out of the sun. 太阳气体射出形成大爆发。
• Spurts of warm rain blew fitfully against their faces. 阵阵温热的雨点拍打在他们脸上。

7 cocoon   

n.茧

参考例句：

• A cocoon is a kind of silk covering made by an insect.蚕茧是由昆虫制造的一种由丝组成的外包层。
• The beautiful butterfly emerged from the cocoon.美丽的蝴蝶自茧中出现。

8 envelops   

v.包围，笼罩，包住( envelop的第三人称单数 )

参考例句：

• He glued many envelops yesterday. 他昨天用胶粘了许多信封。 来自辞典例句
• Ask your friends or mother and father to save used envelops for you. 让你的朋友或父母为你留下用过的信封。 来自英语晨读30分（高二）

9 barrage   

n.火力网，弹幕

参考例句：

• The attack jumped off under cover of a barrage.进攻在炮火的掩护下开始了。
• The fierce artillery barrage destroyed the most part of the city in a few minutes.猛烈的炮火几分钟内便毁灭了这座城市的大部分地区。

10 tadpole   

n.[动]蝌蚪

参考例句：

• As a tadpole changes into a frog,its tail is gradually absorbed.蝌蚪变成蛙，它的尾巴就逐渐被吸收掉。
• It was a tadpole.Now it is a frog.它过去是蝌蚪，现在是一只青蛙。