The Science and Story of Rainbows
Rainbows fascinate us. We find them in nature, and then expound upon and replicate them in our religions, mythologies, literature, art, and music. In this article we will talk about the science of rainbows, our cultural perception of rainbows, and we will learn how to make a rainbow.
How to Make a Rainbow: What Is A Rainbow?
The bright rainbows that we see in the sky are “primary rainbows,” which are red on the outside of their arcs and violet on the inside. They are caused by the light that is reflected from water droplets. Although we artificially subdivide rainbows into “bands,” the colors present in rainbows are not actually separate from each other. A rainbow is a continuous spectrum of colors. Infamous “double rainbows” appear as a color-inverted second arc above a primary rainbow. Rumored “triple rainbows” are scientifically impossible and cannot naturally occur.
How to Make a Rainbow: Where Do We Find Rainbows?
We can find rainbows wherever we find sunlight shining through airborne water droplets at a low angle. We can find rainbows around rainclouds, waterfalls, and fountains. We perceive rainbows to be brightest when half of the sky is still dark with rainclouds. Sometimes, when the moon is bright enough, we can even find moonbows, or nighttime rainbows. Interestingly, one cannot actually be “under” or “at the end of” a rainbow: even if you are looking at someone who appears to be at the end of a rainbow, from their vantage point, the person sees the rainbow as being still further off yet. This means that rainbows are not actual, physical objects that we can physically approach. So much for pots of gold.
How to Make a Rainbow: Rainbows in Science
Rainbows have fascinated scientists over the course of scientific history. Aristotle, the classical Greek scholar (384-322 BC), was the first major scholar to study the rainbow. Although his theories about the formation of the rainbow were largely incorrect, modern scholars still cite Aristotle’s work as the first serious scientific attempt to understand the rainbow. Aristotle’s work as followed by Seneca, who noticed that rainbows always appear in the opposite direction to the sun, and that rainbows always appear by water. Descartes later saw that the size of raindrops didn’t seem to affect the appearance of rainbows. Finally, Sir Isaac Newton worked with prisms to prove that white light was composed of the light of all the colors of the rainbow.
How to Make a Rainbow: Rainbows in Culture
People have explored the rainbow in every cultural form, from religious mythologies to hilariously incoherent YouTube videos. In the Bible, the rainbow was seen as a symbol of God’s promise to never flood the earth again. In Norse mythology, the rainbow was called the Bifrost Bridge, and was seen as the path between Asgard and Midgard, the realm of the gods and the realm of humans. Irish leprechauns are said to hide their pots of gold at the end of rainbows (a place that is, sadly, impossible to reach). Kermit the Frog and Dorothy from The Wizard of Oz sing about rainbows as symbols for hope. The rainbow has also used as a symbol for gay pride and a flag for the LGBT social movements since the 1970s.
Learn How to Make a Rainbow
You can learn how to make a rainbow by performing the following experiment. First, fill a glass of water almost to brimming and place it on the edge of a kitchen counter. Then place a sheet of plain white paper on the floor a few inches away from the counter. Turn off the lights. Cover the front of a flashlight with two strips of masking tape, leaving only a 1/8 inch aperture, and then shine the light down into the glass of water. This should shine a full spectrum onto the sheet of paper.