Stuff You Should Know – Selects: Rainbows: Delighting humanity since forever

Intro

In this episode of “Stuff You Should Know,” Chuck Bryant and Josh Clark explore the fascinating world of rainbows. They discuss the history, science, and mythology surrounding rainbows, as well as the conditions needed to see them. Join them as they unravel the mysteries behind these beautiful natural phenomena.

Main Takeaways

The Science of Rainbows

• Rene Descartes was the first to describe the modern, accurate theory of rainbows in 1637.
• Newton’s interpretation of the rainbow spectrum is a Newtonian invention and our current interpretation of the colors is based on his work.
• The traditional “ROYGBIV” color sequence is not entirely accurate, as there are arguments for only six colors and Indigo being a later addition.
• To understand rainbows, one must first understand how light works and how it moves through different mediums.
• Light moves at different speeds depending on the medium it travels through, and when it hits a medium at an angle, it can change direction sharply, similar to a shopping cart hitting grass at an angle.
• Refraction is the bending of light, which occurs when it enters a medium that slows it down.
• When visible light hits a prism or a raindrop, it bends at different angles depending on the refractive index, which is determined by the wavelength of the light.
• The different colors of the visible spectrum have different wavelengths, causing them to bend at different angles and separate out into a spectrum of colors.

The Mythology of Rainbows

• Rainbows have inspired countless fairy tales, songs, and legends. They are the greatest graphic design of all time.
• Before Newton, different cultures had different ideas about what made up a rainbow, including Celtic legends about pots of gold at the end of rainbows.
• Rainbows are unusual and don’t happen every day, which is why there is a lot of mythology surrounding them.

Seeing and Understanding Rainbows

• Three conditions are needed to see a rainbow: the sun behind the observer, moisture in front, and the sun shining at a 42-degree anti-solar point.
• To see a rainbow, put your back directly to the sun and turn 42 degrees to the right.
• Each raindrop acts like a prism, separating white light into a colored spectrum inside the raindrop.
• You see one big rainbow because each raindrop shoots one color at you that is angled correctly to your line of sight.
• The only color you pick up on is red because there’s only one color from a raindrop that is angled correctly to you in your line of sight.
• Double rainbows have a dark band between them called Alexander’s band.
• Full circle rainbows are possible and depend on the viewer’s position in relation to the ground.

Summary

The Science of Rainbows

Rainbows are not only beautiful but also scientifically fascinating. Rene Descartes and Isaac Newton made significant contributions to our understanding of rainbows. The bending of light, known as refraction, plays a crucial role in the formation of rainbows. When light enters a raindrop, it bends at different angles, separating into its component colors. The traditional “ROYGBIV” color sequence is based on Newton’s work, although there is ongoing debate about the inclusion of Indigo.

The Mythology of Rainbows

Rainbows have captured the human imagination for centuries, inspiring myths and legends. Different cultures had various interpretations of rainbows, including the belief in pots of gold at the end of rainbows in Celtic folklore. Rainbows are rare occurrences, which adds to their mystical allure and the creation of captivating stories.

Seeing and Understanding Rainbows

There are specific conditions required to see a rainbow, including the positioning of the sun, moisture in the air, and the observer’s angle. By following these conditions, one can witness the magic of a rainbow. Each raindrop acts as a prism, breaking white light into a spectrum of colors. Due to the angle of light refraction, only one color from each raindrop reaches the observer’s line of sight, resulting in the appearance of a single rainbow. Double rainbows, with Alexander’s band between them, and even full circle rainbows are possible under certain circumstances.

Conclusion

Rainbows continue to captivate our imaginations with their vibrant colors and mystical appeal. Understanding the science behind rainbows and the cultural significance they hold adds to the wonder they inspire. The next time you spot a rainbow, take a moment to appreciate the beauty and the scientific principles at work.