What's Actually at the End of a Rainbow?

This St. Patrick's Day, let's settle one of the oldest questions in weather lore: what's actually waiting at the end of a rainbow?

The answer is both a little disappointing and genuinely mind-blowing. There is no end. There never was. And the reason why tells you something remarkable about the nature of light, water, and the way your eyes perceive the world.

A Rainbow Isn't a Thing; It's an Illusion

A rainbow is not an object. It has no fixed location in the sky. It doesn't exist in a specific spot that you could walk to, drive to, or dig under.

A rainbow is an optical phenomenon. A trick of light and water that exists only in relation to where you're standing. When sunlight strikes millions of tiny water droplets in the air at just the right angle (around 42 degrees), the light is refracted as it enters each droplet, reflected off the inside surface, and refracted again as it exits. That process separates white light into its individual wavelengths, spreading red, orange, yellow, green, blue, indigo, and violet across the sky in a perfect arc.