英语听力：自然百科 地球力场 Earth's Force Field—9

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Well, we can't see the magnetic field coming out of the experiment, we can measure them, we can put many different magnetic field sensors², and then map out these magnetic fields were coming out, rotating, changing. It's fantastic. 

 

Interactions between the inner and outer core create what's known as a dynamo. This generates a powerful, stable and self-sustaining magnetic field. This is showing magnetic field patterns: red coming out of the experiment, blue going into the experiment,  nothing like I imagine that would be.

 

Lathrop's mechanical core supports the theory that Earth's magnetic field is produced by a geodynamo in its interior. The motion of liquid metal in the outer core is vital to this process. The geodynamo depends on the flow of hot molten metal in the Earth's core. Does Mars' cold core explain how it lost its magnetic shield? Could the Earth suffer the same fate as Mars? 

 

So, / cooling is gonna continue and eventually the Earth's solid inner core is gonna grow larger, larger, and larger. At some point, it may solidify³ completely, and it's possible that even before it solidifies⁴ completely, the Earth's magnetic field will shut off.

 

Is the South Atlantic Anomaly a sign that the Earth's core is cooling? Lathrop doesn’t think so.

 

People think about the Earth's magnetic field as just being North, South, right? You have a compass, it points North. Everything is simple. But if you look carefully on maps, you notice that magnetic North and geographic⁵ North are not the same thing. That's in part because magnetic pole is actually in Canada. 

 

The magnetic North Pole is illusive⁶. Whenever explorers look for it, they find it in a different place.

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