http://www.ck12.org Chapter 5. Energy
5.83 Using Earth’s Magnetic Field
- Describe Earth’s magnetic field.
- Explain how Earth’s magnetic field protects organisms from solar radiation.
- Describe how some animals use Earth’s magnetic field for navigation.
You may recognize the eerie green glow in this cold northern sky as the northern lights, or aurora borealis. But do
you know what causes the northern lights? Earth’s magnetic field is a major factor.
Earth’s Magnetic Field
Like a bar magnet, planet Earth has north and south magnetic poles and amagnetic fieldover which it exerts
magnetic force. Earth’s magnetic field is called the magnetosphere. You can see it in theFigure5.180.
Like an Umbrella
The sun gives off radiation in solar winds. You can see solar winds in theFigure5.180. Notice what happens to
solar winds when they reach the magnetosphere. They are deflected almost completely by Earth’s magnetic field.
Radiation in solar wind would wash over Earth and kill most living things were it not for the magnetosphere. It
protects Earth’s organisms from radiation like an umbrella protects you from rain.
Q:Now can you explain the northern lights?
A:Energetic particles in solar wind collide with atoms in the atmosphere over the poles, and energy is released in
the form of light. The swirling patterns of light follow lines of magnetic force in the magnetosphere.