Magnetic Field of Earth

Our earth acts like a magnet too. Deep beneath the earth’s surface is a sphere of hot, molten rock and metal. The metal is mostly melted iron and nickel at an extremely high temperature, about 4,000-9,000^oF. This region is called the Outer Core. Scientists believe that the earth’s magnetism comes from the vigorous circulation of this molten rock and metal in the earth’s outer core.

Where are the Earth’s Magnetic Poles?

As you well know, the earth has the Geographic North Pole and Geographic South Pole. The earth spins around an imaginary line drawn through these two poles. These geographic poles are fixed points on the earth’s surface – they remain exactly where they are forever.

The magnetism of earth also creates the Magnetic North Pole and the Magnetic South Pole. These magnetic poles are close to the geographic poles but not always at the same place on the earth’s surface – they tend to move around! The reason for this is the circulating currents of liquid metal in the earth’s outer core, which constantly move the magnetic poles.

Therefore, just as any bar magnet has two ends where the power of the magnet is the strongest, the earth also has the magnetic poles where the power of the magnet is the strongest.

Unlike the symmetrical pattern of iron filings which we observe around a bar magnet, the earth’s magnetosphere is pushed in on the side which faces the sun and pulled out on the side away from the sun. This is because Solar Radiation or Solar Wind from the sun has its own magnetic influence which acts on earth’s magnetosphere and pushes it away. This causes the earth to have a magnetic “tail” on the side that does not face the sun.

The magnetosphere protects us from harmful radiation coming from the sun. Without the magnetosphere the solar wind would have blown away our precious atmosphere, making life on earth impossible. It is also responsible for the beautiful Aurora Borealis or Northern Lights which we get to see in the far northern hemisphere.

Check Point

1. The circulating molten rock and metal way below the earth’s surface, which is responsible for earth’s magnetism, is called the _______.
2. Which statement is true?
   1. The earth’s geographic and magnetic poles are always the same.
   2. The earth’s geographic poles often change positions with the magnetic poles.
   3. The magnetic poles are never at one location and tend to move around.
   4. The power of earth’s magnetism is strongest at the geographic poles.
3. The magnetic field around earth is called the ______.
4. The magnetic tail is caused because of _______.
5. Which statement is true?
   1. The magnetosphere protects us from the sun’s harmful radiation.
   2. The magnetosphere helps preserve our atmosphere.
   3. The magnetosphere creates beautiful Northern Lights.
   4. All of the above.

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