英语听力：自然百科 地球力场 Earth's Force Field—8

 Easily confused by this idea, there has a big thawed¹ iron inner core, so that I think it's just the bar magnet, just permanent magnet frozen in nad, and that's where causes all the magnetic field. But it's too hot inside the Earth, that can't happen when the temperature gets hot enough, magnets turn off.

 

Permanent magnets stop working at 1,200 degrees Fahrenheit². So some other process must be generating Earth's magnetic field. To find out more, professor Dan Lathrop embarks³ on a very ambitious experiment. At the University of Maryland, he and his team build a 10-foot mechanical model of the Earth's core. 

 

I think we want to understand is why some planets generate magnetic field, and why others have no magnetic field. So, by building experiments, we could hope to understand the conditions when it works and when it doesn't. What's the switch / why sometimes a planet comes alive magnetically and why sometimes they will mean dead.

 

Inside this sphere, is a solid iron bowl, surrounded by 13 tons of churning liquid metal. Lathrop uses molten sodium⁴ instead of iron, because of its lower melting point. So we get a rotating outer sphere, holds liquid sodium and its man-to-man mixed iron and the Earth's core..

 

 

o limit Earth's rotation⁵. Those drive the outer sphere of the vas, 4 revolutions per second and inner core of the vas, 15 revolutions per second. 

 

So, let's go, give it a spin. If it succeeds, Lathrop's experiment will advance our understanding of how our magnetic field is generated. Looks good, seeing 26 turns of rotatings, metal on liquids up close to the sound, so really had no idea with a big deal like that. That is, it's wavering turns.

 

1 thawed   

解冻

参考例句：

• The little girl's smile thawed the angry old man. 小姑娘的微笑使发怒的老头缓和下来。 来自《简明英汉词典》
• He thawed after sitting at a fire for a while. 在火堆旁坐了一会儿，他觉得暖和起来了。 来自《简明英汉词典》

2 Fahrenheit   

n./adj.华氏温度；华氏温度计(的)

参考例句：

• He was asked for the boiling point of water in Fahrenheit.他被问到水的沸点是华氏多少度。
• The thermometer reads 80 degrees Fahrenheit.寒暑表指出华氏80度。

3 embarks   

乘船( embark的第三人称单数 )； 装载； 从事

参考例句：

• Patricia is a free-spirited girl who embarks on an erotic odyssey. 翠茜亚是个任性少女、毅然踏上一次性爱之旅。
• Passenger train driver: Punctually embarks. 客车司机：准时出发。

4 sodium   

n.（化）钠

参考例句：

• Out over the town the sodium lights were lit.在外面，全城的钠光灯都亮了。
• Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。

5 rotation   

n.旋转；循环，轮流

参考例句：

• Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
• The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。