英语听力：自然百科 地球力场 Earth's Force Field—5

 If we could flip¹ a switch and just turn off the Earth's magnetic field, it will take about 15,000 years to disappear, based on the rate of decay of the field that we've seen over the last 150 years. It's currently decaying at a rate that would see and disappear in 1500 years.

 

Earth's magnetic field is decaying fast. Discovering the consequences for our planet, is a top priority. Earth's magnetic field is fading. But what would happen if it disappeared completely? The answer lies on another planet in the solar system.

 

In 1996, NASA launched the Mars Global Surveyor, its mission to unlock the red planet's secrets.

 

Of all the planets in the solar system, Mars is the most similar to Earth. Both planets are made from the same materials. They each have / hard crusts, dense² cores and relatively³ similar atmospheric⁴ chemistry. Scientists believe that as on Earth water flowed on Mars' surface, but that was billions of years ago. Today, the planet is a frozen desert. To find out why, the orbiting Mars Global Surveyor collects data from the red planet. Professor Ben Vice⁵ uses this data to reconstruct its past.

 

Unlike the Earth, Mars' today does not have a global magnetic field generated in its core. But if you will walk around the ancient southern highlands of Mars, you'll be walking in many places and fields as strong as the Earth. But it is very complicated, almost like spaghetti, pointing, you know, in different directions, not pointing in North at all.

 

1 flip   

vt.快速翻动；轻抛；轻拍；n.轻抛；adj.轻浮的

参考例句：

• I had a quick flip through the book and it looked very interesting.我很快翻阅了一下那本书，看来似乎很有趣。
• Let's flip a coin to see who pays the bill.咱们来抛硬币决定谁付钱。

2 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

3 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

4 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

5 vice   

n.坏事；恶习；[pl.]台钳，老虎钳；adj.副的

参考例句：

• He guarded himself against vice.他避免染上坏习惯。
• They are sunk in the depth of vice.他们堕入了罪恶的深渊。