All along my hike, my eyes are drawn to the colors in front of me and at my feet. With a break in the trees ahead of me I can see a glimpse of the horizon. With the sun behind my back, I can see the faint outlines of a rainbow tenderly painting the sky. To this point, pretty much all the color mechanisms we’ve talked about were similar. Essentially, it worked like this. White light, containing a balanced mixture of the spectral colors, shines onto an object (flower, crystal, blood, anything). An atom or molecule within the object absorbs light at a specific wavelength. The energy from that light could do many different things: excite electrons into high energy states, or cause the molecule to vibrate, or even drive the process of photosynthesis within a plant. The key is that part of the visible spectrum has been removed due to this absorption, and thus the constituent colors contained within the light reflecting off the object is no longer in balance. Thus, we see green leaves, or blue blood, or a red ruby. To understand the rainbow, we’ll need to discuss color originating from a very different mechanism – refraction.