地球磁场

How can you find your way?
::你怎么能找到自己的路吗?

You can use Earth's  magnetic field  to tell you where you want to go. A  compass  needle aligns with Earth’s magnetic field. People can navigate by finding magnetic north. If you know where north is, you can figure out how to get anywhere. A compass is great for finding your way when you're out in the field!
::您可以使用地球磁场来告诉你要去哪儿。 一个罗盘针与地球磁场相吻合。 人们可以通过找到北面磁场来导航。 如果您知道北面的位置, 您可以找到任何地点。 指南针对于在野外找到自己的路很有帮助 !

Earth’s Magnetism
::地球的磁权主义

Earth has a  magnetic field  ( Figure   ). The magnetic field behaves like a giant bar magnet inside Earth. If you have a large bar magnet, you can hang it from a string. Then watch as it aligns itself in a north-south direction. It does this to line up with Earth’s magnetic field.
::地球有磁场( 图 ) 。 磁场在地球内部的行为就像磁铁磁铁一样。 如果您有大块的铁磁铁, 您可以挂在绳子上。 然后看着它以北向向南。 它这样做是为了与地球磁场连成一行。

The magnetic field has north and south poles. The magnetic poles do not exactly match the geographic poles. So the North Magnetic Pole is not the same as the geographic North Pole. The same is true of the South Pole. The magnetic field is created by the movement of molten metal in the outer  core .
::磁场有北极和南极。 磁极与地理极不完全吻合。 因此北磁极与北极不同。 南极也是如此。 磁场是由外核熔金属运动造成的。

Earth’s magnetic field extends several thousand kilometers into space. It shields us from harmful radiation from the   ( Figure   ).
::地球的磁场向太空延伸数千公里。 它保护着我们免受来自(图 ) 的有害辐射。

Magnetic Reversals
::磁变转

Something very strange has happened many times during Earth's history. The planet's magnetic field flipped! The North Magnetic Pole became the South Magnetic Pole. The South Magnetic Pole became the North Magnetic Pole. Scientists are not sure why this happens. The  fact  that it does happen is useful to scientists. In the chapter  Plate Tectonics , you'll learn how.
::地球上的磁场翻转了! 北磁极变成了南磁极。 南磁极变成了北磁极。 科学家们不知道为什么会发生这种情况。 确实发生这种情况对科学家是有用的。 在“ 热电图” 一章中, 你会知道如何发生。

Summary
::摘要

• Earth's magnetic field is like a bar magnet through the planet.
  ::地球的磁场就像块磁铁 穿过地球

• The magnetic field is generated by convection in the liquid outer core.
  ::磁场是通过液体外核的对流产生的。

• Occasionally the magnetic field flips. The North Magnetic Pole becomes the South Magnetic Pole and the South Magnetic Pole becomes the North Magnetic Pole.
  ::有时是磁场翻转。北磁极变成南磁极,南磁极变成北磁极。

Review
::回顾

1. Why does Earth have a magnetic field?
   ::为什么地球有磁场?

1. Why is it important for Earth to have a magnetic field?
   ::为什么地球必须有一个磁场?

1. What is a magnetic field reversal?
   ::什么是磁场逆转?

Explore More
::探索更多

Use this resource to answer the questions that follow.
::使用此资源回答下面的问题 。

1. What generates Earth’s magnetic field? Why is the magnetic field important?
   ::地球磁场是什么产生的? 为什么磁场重要?

1. What is a magnetic field flip? Roughly how often does it happen?
   ::磁场翻转是什么?

1. Why do scientists interested in Earth’s magnetic field collect cores from rocks at the Mid-Atlantic Ridge?
   ::为什么对地球磁场感兴趣的科学家会从中大西洋海脊的岩石中采集岩芯?

1. When was the last major magnetic field flip?
   ::上次主要的磁场翻转是什么时候?

1. How do ancient pottery give scientists clues about Earth’s magnetic field? Why is it more precise than rocks?
   ::古代陶器如何为科学家提供地球磁场的线索? 为什么它比岩石更精确?

1. When was Earth’s magnetic field strength high and when was it lower (note that BCE means before current era and years correlate with the BC and AD system)?
   ::地球磁场的强度是何时高的,是何时低的(注意BCE是指在当今时代和年代之前与BC和AD系统相关联)?

1. What has happened to magnetic north since it was first located in the early 19th century? How has the field changed in the past two centuries?
   ::自19世纪初磁场首次位于北纬19世纪初以来,磁场发生了什么变化?在过去两个世纪中,磁场是如何变化的?