Often, as you watch a fireworks display, you will see a large burst that starts as one color, and then the entire burst changes to a different color. How do they do that?
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While playing with my camera, I decided to take a closeup of my eye. When we talk about eye color, we are talking about the color of the iris, the part of the eye that opens and closes the pupil. Eye color varies quite a bit, ranging from blue to green to brown to grey. How many different pigments are there for eye color?