Can I touch a rainbow? Azhar, Saudi Arabia
We could touch rainbows if they were physical objects. But rainbows, unfortunately, are not physical objects. A rainbow is "a distorted image of the sun" whose light raindrops bend, reflect and scatter on its way to our eyes, write meteorologists Raymond L. Lee, Jr. and Alistair B. Fraser in The Rainbow Bridge.
Optically speaking, an image is "any collection of light rays that appears to come from a more-or-less well-defined set of directions," Lee says. So an image is made of light. The question remains: can we touch the image called a "rainbow."
The American Heritage Dictionary defines touching: "To cause or permit a part of the body, especially the hand or fingers, to come in contact with so as to feel: reached out and touched the smooth stone."
The Rainbow Bridge, Rainbows in Art, Myth, and Science by Raymond L. Lee and Alistair B. Fraser 2001. University Park, PA: Pennsylvania State University Press. Image Formation for Plane Mirrors by Tom Henderson, Physics Classroom Tutorial What causes rainbows, WeatherQuesting Rainbows by Alistair Fraser Atmospheric Optics by Les Cowley Rainbows, by Rod Nave, Hyperphysics (Answered March 9, 2009)
Readers' Answers
• Yes, you can catch a rainbow. While driving in a valley in England I had the unique experience of driving through the end of a rainbow. John Albinson, Kingston, Ontario, Canada
• Yes! Since a rainbow is the reflection of light on tiny water droplets, if you're close enough to touch the water that's reflecting the light, then you are basically touching the rainbow. Try it with a garden hose spray nozzle that can be adjusted to a fine mist. On a sunny afternoon, spray it toward your shadow, and you should see a rainbow that, if the angles are right, is close enough to touch. Anthony Kerschen, McDonough, Georgia, USA
• In short, you can touch someone else's rainbow, but not your own. A rainbow is light reflecting and refracting off water particles in the air, such as rain or mist. The water particles and refracted light that form the rainbow you see can be miles away and are too distant to touch.
However, it is possible to touch the water particles and refracted light (if you agree that you can touch light) of a rainbow that someone else is viewing. Imagine flying an open-co*ckpit plane through water particles that are refracting light into a rainbow for someone viewing it from a distant vantage point.
There is one instance where you can touch your own rainbow, though, if you consider the refracted light from a garden hose spray to be a rainbow. If you have ever tried this you may have discovered what I did - that rainbows are ethereal and that waving your hand through the mist has no effect on them and makes it seem as though they exist in some other realm. Janet Warner, Durham, North Carolina, USA
• Yes, you can touch a rainbow. But simply not how most humans typically observe a rainbow. I lived beside a lake in Arkansas, for 14 years. Every summer I rode a jet ski on that lake. Occasionally, the light would be perfect, would interact with the spray behind the jet ski and produce a small rainbow. Theoretically, I could have reached back, and touched any part of it. So, yes, but on a smaller scale than most perceive. Will McBride, Colorado, USA
• The rainbow is an optical phenomenon of refraction. When sunlight hits a drop of water, it breaks down into colors at a certain angle, and it is also seen only from a certain angle.
If you move from the position where you saw the rainbow to a different position, you will see a different rainbow, reflected from different water drops. And, if you get out of this angle altogether, the rainbow just disappears. This can be easily experienced within reachable distance, when seeing the rainbow produced by a nearby fountain-spray.
So, if you move from where your eyes touch the rainbow, to a position where your hands could touch it, you will only be touching the air where it was, but the rainbow will not be there for you see that you do! In other words, you can never get hold of the rainbow! Elisheva, Jerusalem
April Holladay lives in Albuquerque, New Mexico. Her column, WonderQuest, appears every second Monday of the month on globetechnology.com. To read April's past columns, please visit her website. If you have a question for April, visit this information page.
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