英语听力：自然百科 地球力场 Earth's Force Field—12
时间：2014-05-26 07:11:07
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（单词翻译）
Six years later, they come to believe these light flashes are the results of high energy, heavy cosmic rays penetrating1 the spacecraft and the crew members' eyes.
These/ protons or electrons, just very, very high energy, ripped / part of atoms, spring out from the sun. In terms of manned space travel, if you're outside the magnetosphere in a big solar storm, large amounts of radiation passing through your body,
dire2 / health consequences.
These particles can become trapped inside a region of the magnetosphere known as the Van Allen Belt. They present a real hazard to astronauts. At least 39 astronauts have developed some kind of eye
cataract3, 4 or 5 years after exposure to this dangerous radiation. As our protective magnetic field weakens, the risk to life increases.
Professor Gary Glatsmire wants to know how much weaker the Earth's magnetosphere is going to get. He creates a
remarkable4 computer model of Earth's magnetic field.
We can't reproduce exactly what the Earth has done in the past or what it is doing right now. What we are trying to do is get the model to simulate something that's
qualitatively5 similar.
Glatsmire runs the computer model continually. Each year of real time represents 100,000 years of simulated time. He observes how the magnetic field evolves over the
millennia6. Around 36,000 years into the simulation, something unusual happens.
After I've been away for a couple of weeks, I came back and looked at the results and then realized that it had reversed, and it was exciting.
Glatsmire's experiment shows the magnetic North and magnetic South switch positions.
This is the surface of the model Earth, this is the surface of the model core. Field is directed inwards here and
outwards7 there, field is much more complicated on the top of the core. Now the reversal is occurring, the field is now drifted outwards there and inwards there.
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