Simulation of the Earth's Magnetic Field

The image below is a cross section through the Earth (the blue circle). As you move your cursor over the image, an arrow will be beneath your cursor.

The direction of the arrow is the direction to north (that is, the direction a magnetized needle would point). Since this is a cross section, this shows how the Earth's field points up or down.
The area of the arrow is proportional to the strength of the magnetic field at that point. When you move the cursor inside the Earth's cross section, the arrow turns red and only shows the direction.
In addition, there are now numerical outputs showing the inclination of the Earth's field (upper right), your latitude, and the strength of the dipole field (when outside the Earth). Clicking down causes the field to reverse polarity--colors will change and the direction is now reversed, as happens every so often with the Earth's field.
If you don't see anything below, get the current Shockwave plugin from Macromedia at http://www.macromedia.com/shockwave/download/