Color is such an everyday phenomenon that we don't usually give it a lot of thought. But colors can produce surprising effects, for example, in the way they mix together. We can also use color directly in science to learn about the universe.

The activities for this topic explore color in three different ways.

• Made from Dots. Many printed color pictures are not solid color at all, but rather a sea of dots in three or four different colors. You will explore how the process works in this activity.

• Colored Shadows (Requires Java.) Funny things happen when colored lights cast shadows. You will use a simulation of such lights to see how this works. (See the background page for a link to instructions on how to do the simulation as a class activity.)

• Stellar Spectra. Astronomers can look at starlight and tell what the star is made of. You will look at light, separated into a spectrum, and figure out the elements from the spectral lines you see.