Rainbow Colors Always Appear in the Same Order

The colors of the rainbow always show up in the same order: red, orange, yellow, green, blue, indigo and violet. It's organized by wavelength. Red, with the longest wavelength, is on the outside, while violet, with the shortest, is on the inside.

The seven colors of a rainbow can be remembered with the mnemonic "ROYGBIV," or Roy G. Biv, which stands for Red, Orange, Yellow, Green, Blue, Indigo and Violet. These colors are called spectral colors.

This sequence corresponds to the visible spectrum of light that we can see with the naked eye. Each color transitions smoothly into the next, creating the familiar gradient.

In nature, most rainbows exist because of sunlight and rain. When sunlight hits the water droplets in the air, the white light splits into a spectrum of colors that bend (or refract) at different angles. This is what gives us the eye-catching arc we call a rainbow.

Each angle separates the sunlight into its component colors, creating a spectrum. This process happens inside countless droplets, and the different angles of refraction cause the colors to spread out, with each droplet contributing just one color to your view. This all combines to produce the rainbow we see.

If you're high enough in the sky, the rainbow actually appears as a circle. But from the ground, we usually see only one arc.

Isaac Newton was the first to figure out why rainbows exist. When he shone sunlight through a prism, it split into the colors of the rainbow. Before Newton's discovery, people didn't realize that white light contained so many colors of the visible spectrum.

Newton chose to include indigo as a separate color, even though it's been debated because it's hard for the human eye to distinguish from blue and violet. He settled on seven different shades because he was comparing the colors of the rainbow to the notes in a musical scale.

Prisms work by bending light at different angles, just like water droplets do in a rainbow. When white light enters a prism, it slows down and changes direction due to the prism's shape and material.

This process is called dispersion. Red, with its longest wavelength, bends the least, while violet bends the most.

Prisms give us a controlled way to study the visible spectrum, showing us that the rainbow effect is no coincidence but a fundamental property of light.

The human eye detects the visible spectrum using special cells called cones. These cones are sensitive to different wavelengths of light, which we perceive as colors.

Red light, for example, has the longest wavelength, while blue light has a shorter one. The range of wavelengths we see as visible light stretches from about 380 nanometers (violet) to 750 nanometers (red).

Colors like pink, gray and brown aren't in the rainbow because they result from combinations of wavelengths that don't appear as pure spectral colors. For example, pink is a mix of red and violet, which are on opposite ends of the spectrum.

Meanwhile, dark shades of colors, like deep purples or muted greens, don't appear because they aren't bright enough to be separated by the refracting water droplets.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.