Earth has an immense magnetic field surrounding it, just as there is a magnetic field
around a bar magnet.
Earth’s magnetic poles are not located at the geographic poles.
• The angle between geographic north and magnetic north (the north to which a compass needle points) is known as magnetic
Magnetic declination changes over time because the magnetic poles are slowly moving.
• Earth’s magnetic fields extend into space, which contains electrically charged particles.
• Earth’s magnetic field affects the movements of electrically charged particles in space.
• Charged particles also affect Earth’s magnetic field.
of electrically charged particles that affect Earth’s magnetic field are:
– Van Allen
Belt: Two regions between 1000 and 25000 Km above Earth’s surface containing electrons and protons moving at very high
Sources of electrically charged particles that affect Earth’s magnetic field are:
– Solar Wind: A stream of electrically charged particles flowing at high speeds from the sun.
– Earth and other planets experience a solar wind.
– The solar
wind pushes against Earth’s magnetic field and surrounds the field.
– The region
of Earth’s magnetic field shaped by the solar wind is called the magnetosphere.
• The region of Earth’s magnetic field shaped by the solar wind is called the magnetosphere.
• When charged particles get close to Earth’s surface, they interact with atoms in the atmosphere.
• This causes the atoms to give off light.
• A glowing region
caused by charged particles from the sun is called an aurora. In the Northern Hemisphere, an aurora is called the Northern
Since Earth produces a strong magnetic field, Earth itself can make magnets.
• Earth’s magnetic field also acts on rocks that contain magnetic material.
• Magnetic Rock in Grand Marais, MN
• Earth can leave a magnetic
history of itself
Molten material seeps up through the ocean floor.
– When it is molten, the iron it contains lines up in the direction of Earth’s magnetic field.
– As the rock cools and hardens, the iron is locked in place.
does Earth’s magnetic field change direction?
magnetic field arises from the motion of the molten metal in the Earth’s core.
– Changes in the flow of that metal result in changes in Earth’s magnetic field.
– Details of this theory have not yet been worked out!