To What End, Rainbows?

I was driving away from the house with my boys to run some errands.  I was silently ruminating about how we had managed to get loaded up in the car right when the rain got significantly heavier when I looked up in the sky and saw a clearly defined rainbow.

I find rainbows exciting, and that particular rainbow stripped my rain induced annoyance away.  My eldest finds rainbows exciting too, as was evidenced by his elation when I pointed it out to him in the sky after we stopped at a light.  I asked him what colors he saw.  He said, "Blue, orange, yellow and red."  I'm not sure if I got his order right or not, but he enumerated all but purple (the purple portion was rather dim besides).  He was also quick to point out that blue was his favorite.

Rainbows are one of those great science treats out there.  Kids love them.  Adults can love them, too, if they remember to.  Simple droplets of water in the air offer a natural glimpse of the prismatic nature of white light, begging for someone to look and wonder, "How?"

It turns out some notable people started wondering how quite a while ago.  A quick trip to Wikipedia confessed a litany of names, beginning with Aristotle, and including an Arab physicist (Ibn al-Haytham), a Persian philosopher (Ibn Sīnā), a Chinese scholar (Shen Quo), a Persian astronomer (Qutb al-Din al-Shirazi), the French natural philosopher René Descartes, and Sir Isaac Newton (let's just call him a scientist... he had he wore too many hats to list them all) all did their part in furthering scientific explanations of rainbows.  Many other didn't make my far from exhaustive list.  So, if a rainbow has ever inspired your wonder and curiosity, you're in some good company.

One of the things I find most fascinating about rainbows is their natural gratuity.  There are many beautiful phenomena in nature that inspire us to ask questions.  Yet most of them have a rather clear purpose.  From the amazing star forming regions in Orion's belt where the most fundamental necessity for our kind of life, the creation of a star, is being repeated time and again, to the amazing color spread of a male peacock's feathers, carefully crafted through evolutionary time to woo potential mates, beauty comes with purpose, there is function to form.  There is no obvious useful purpose served by rainbows.  Rainbows are a special treat endowed by a Universe that rewards those who know how to forget getting soaked long enough to appreciate a little bit of color in life.

Image Credit: Wikipedia