http://www.ck12.org Chapter 24. Magnetism
CHAPTER
24 Magnetism
Chapter Outline
24.1 Magnets and Magnetism
24.2 EARTH AS AMAGNET
24.3 REFERENCES
The eerie green lights in the sky in this photo are called northern lights, or aurora borealis. They are caused by
Earth’s magnetic attraction for electrically charged particles given off by the sun. When the particles collide with
gas molecules in Earth’s atmosphere, the molecules give off light. The same thing also occurs in the southern
hemisphere, where the lights are called southern lights, or aurora australis. Northern and southern lights are visible
mainly near the poles, and they are typically green like the northern lights shown here. In this chapter, you’ll learn
how magnetic force can cause such spectacular effects and why Earth is a giant magnet.
Nick Russill.www.flickr.com/photos/nickrussill/ 150410999 .CC BY 2. 0.