From site: Why are things colored? There are three causes. Repeatedly over and over in innumerable variety, they create our colorful world. Light is made in the yellow glow of a candle. Light is lost when sunlight filters through stained glass. Light is moved when the sky turns crimson at sunset...
Scholars have learned that all the colors in the universe originate from a mere fifteen fundamental physical causes. These causes appear over and over, lending color to the world around us. Some common causes seem logical -- for example, both light bulbs and candles are colored by incandescence -- and others are surprising -- did you know that the colors of peacock feathers and bubbles are both caused by interference?
