1·Messenger will explore the surface of Mercury, its crust, its atmosphere and even its magnetic field.
“信使号”将探索水星的表面、地壳、大气，甚至其磁场。
2·Geomagnetic activity, the natural variations in Earth's magnetic field, it fluctuates in 11-year cycles.
地磁活动是地球磁场的自然变化，其波动周期为11年。
3·At the Earth's surface, these tempests can be detected by changes in the strength of the Earth's magnetic field.
在地球表面，可以通过改变地球磁场强度来检测这些风暴。
4·When the magnetic field is at its strongest, and sunspots at their most plentiful, they cluster close to the equator.
当磁场最强，太阳黑子最丰富的时候，它们会聚集在赤道附近。
5·This metallic core gives Earth its characteristic magnetic field, which has played an extremely important role in the history of our planet.
这种金属核赋予地球特有的磁场，在地球的历史上发挥了极其重要的作用。