英语听力：自然百科 地球力场 Earth's Force Field—15

搜索关注在线英语听力室公众号：tingroom，领取免费英语资料大礼包。

 

 

 

During this process of reversal, the magnetic field drops very significantly and intensively. And it's happened many, many, many times rather in Earth history, / you know, they're 4.5 billion years old, and I'm saying it happens every a few hundred or thousand years or so. 

 

 

 

 

 

Years of research revealed that the last reversal occurred 780,000 years ago. 

 

 

 

It's easy to understand why there is such an interest and the possibility of a magnetic reversal. The last magnetic reversal occurred more than three quarters of a million years ago, and so in a real sense well overdue³ for another, and so the question is not if another reversal will occur, but when. 

 

 

 

Many scientists now believe that the South Atlantic Anomaly is the start of a global magnetic field reversal, the decay of our magnetic field will accelerate with serious consequences for life. 

 

 

 

Kind of radiation we are talking about is known to damage DNA⁴ and RNA and cell's structure, and it is a serious cause of cancer incidents. 

 

 

 

On Earth, magnetic field reversals are comparatively rare and erratic⁵, but on our nearest star, they occur far more frequently. 

 

 

 

Every 11 years, the direction of the Sun's magnetic field flips⁶. So the Sun's magnetic field isolates⁷ regularly, whereas the Earth has these long periods, whereas the E.U. magnetic field's direction remains⁸ more or less constant and then it flips suddenly. 

 

 

 

Although the Sun's magnetic field isn't generated in exactly the same way as the Earth, scientists still observe it closely. 

 

 

 

So you get these very different dynamos operating under the same laws of physics under glow of different environments, so by studying both of them and comparing them, we learn more about both possibilities

分享到：