# using earths magnetic field

## earths magnetic field

Like a bar magnet, planet Earth has north and south magnetic poles and a magnetic field over which it exerts magnetic force. Earths magnetic field is called the magnetosphere. You can see it in the Figure 1.1.

## finding the way

Another benefit of Earths magnetic field is its use for navigation. People use compasses to detect Earths magnetic north pole and tell direction. Many animals have natural compasses that work just as well. For example, the loggerhead turtle in the Figure 1.2 senses the direction and strength of Earths magnetic field and uses it to navigate along migration routes. Many migratory bird species can also sense the magnetic field and use it for navigation. Recent research suggests that they may have structures in their eyes that let them see Earths magnetic field as a visual pattern.

## like an umbrella

The sun gives off radiation in solar winds. You can see solar winds in the Figure 1.1. Notice what happens to solar winds when they reach the magnetosphere. They are deflected almost completely by Earths magnetic field. Radiation in solar wind would wash over Earth and kill most living things were it not for the magnetosphere. It protects Earths 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.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

earth has north and south magnetic poles like a bar magnet.

``````-->  a. true

b. false
``````

how does earths magnetic field protect the planet?

``````a) it holds the atmosphere in place.

b) it deflects solar winds.

c) it protects earths organisms from radiation.

-->  d) two of the above
``````

there would be no northern lights without the magnetosphere.

``````-->  a. true

b. false
``````

animals that use earths magnetic field for navigation include

``````a) loggerhead turtles.

b) migratory birds.

c) humans.

-->  d) all of the above
``````

people have only recently started using earths magnetic field for determining direction.

``````a. true

-->  b. false
``````

some birds may be able to sense earths magnetic field lines as a visual pattern.

``````-->  a. true

b. false
``````

## diagram questions

No diagram questions associated with this lesson